Oil Change Caveats

Print Friendly, PDF & Email

Is it once very 3,000 – or once every 10,000?

The articles one finds online try very hard to be definitive – which is why they’re often inaccurate. For example, I recently came across an article that stated with the certainty of the Dear Leader that “savvy car owners know that changing the oil on their vehicle every 3,000 miles is overkill and a waste of money.”

And also that “…most vehicles built in the last twenty years can go 7,500 to 10,000 miles before a change of oil and oil filter is needed.”

Well, actually, not necessarily.

The honest answer about oil and filter changes is – it depends.

It depends, for one, on your particular vehicle. And it also depends on how that vehicle is driven – including when it is driven, how often (or not) and under what conditions. It depends on the type of oil and filter you use, too.

Just for openers.

First, your vehicle:

The universal statement that you are “wasting money” if you change your oil every 3,000 miles could lead to wasting a lot more money – on engine work –  if it goes against what’s right for your particular car.

If you have a car built before the late 1980s, for example it may still be necessary to change the oil every 3,000 miles – just as the factory  recommended when it was new. The chief reason being that cars of this vintage (and older) have carburetors rather than fuel injection, which is a less precise way of metering fuel to the engine. Rather than a high-pressure mist, fed to the engine in just the right ratio, a carburetor may be running “rich” (feeding he engine too much gas) and some of the gas may still be in liquid form. Too much gas – and any “raw” gas –  will often make its way to the oil sump in the bottom of the engine, where it will act as a solvent, washing the protective film of oil off critical parts and diluting the oil’s ability to protect the engine.

You don’t want gas in your oil – and only draining it will get rid of it.

Or, your vehicle may be newer and equipped with EFI – but also have a lot of miles on it. In which case, the engine may not be as tight as it was when new. In which case, contaminants (such as blow-by, which gets past worn piston rings) accumulate in the oil faster than they used to . In which case, you ought to shorten oil/filter changes to extend the useful life of the engine as well as get optimum mileage out of it.

Second, how do you drive it?

A car that is infrequently driven should have its oil changed more often even if the miles haven’t accumulated to the recommended changeout interval – for similar reasons to those discussed above. Corrosive acids and condensation can form inside a lightly-used engine and if it’s not boiled off by use (or captured by the filter as the oil circulates through the system) it will accumulate to the point that the oil needs to be drained to get the contaminants drained. Lightly-used engines are also more prone to sludge build-up.  If you have a vehicle you just use to run to the store that’s a mile down the road and back – and that’s it – you probably ought to shorten your oil/filter changeout intervals.

And of course, the opposite sort of use – that is, hard use – is another reason to reduce service intervals. Most automakers specifically recommend this in the owner’s manuals they give you with the car. The problem is that some people don’t read the manual and so have no idea that their slow-motion, bumper-to-bumper commute to work and back each day constitutes “severe” or “heavy duty” use – and that the advertised 5,000 or even 10,000 mile changeout intervals are only for “normal” driving conditions. Read your manual.

Be sure.

Type of oil and filter –

This one’s probably the most important factor of all. If you use the lowest-price, bulk-bought, no-name-brand, who-knows-where-it-came-from oil and filters you could be risking engine damage just be starting it – let alone using that stuff for 5,000 or (forget about it) 10,000 miles. Especially if your car was designed to use semi (or fully) synthetic oil and high-performance filters. In fact, using less-than-the-minimum recommended quality of oil, or a filter that does not meet the vehicle manufacturer’s specifications for flow or size of particles captured, pressure capacity, durability, etc. can void your warranty coverage and leave you holding the bag (of parts) if your engine grinds itself to death as a result of an oil or filter-related failure.

There is also the issue of viscosity – thickness, or flow resistance. Modern engines have very tight internal tolerances, which is one of the reasons (in addition to reducing friction) why the vehicle’s manufacturer may recommend a very specific viscosity, such as 5W-30 rather than a heavier 10w-40. If you make the mistake of using the heavier oil because “it’s what they had” or “it was on sale,” you may end up learning the hard way – the expensive way – how important it is to use the recommended viscosity oil, as well as the recommended quality oil.

Conversely, if you use very high-quality oil – especially semi and full synthetics and top-drawer filters such as those made by Ames, Mobil 1 and so on – then you probably can go for longer (and run your car harder, too) without much, if any, risk to your engine. Synthetics will usually give you noticeably better cold-start performance and driveability, too. But they’re expensive – typically 40-50 percent more per quart than conventional mineral oil. Ditto the filters.

So, the Catch-22 here is that while you can go longer between oil/filter changes, each oil and filter change will probably cost you significantly more. In the end, your net cost may be about the same – though you’ll save some time by not having to change the oil/filter quite as often.

Whichever type/brand of oil (and filter) you use, be absolutely sure it meets the vehicle manufacturer’s minimum SAE requirements  before you use it. The SAE rating will be listed in your vehicle owner’s manual. (see here for more info).

Throw it in the Woods?


  1. I had a 1993 Dodge Grand Caravan. It was a great car to carry sales samples in. I averaged 30-40K miles each year and tried to change the oil every 3,000 miles. When I finally got rid of the car, I had 406,000 miles on the original engine. Unfortunately, the transmissions lasted only about 100,000 each. It did have a stainless steel exhaust system which also lasted 406,000 miles.

    • One thing I’ve noticed over the years is that almost any vehicle, if treated decently, can be made to last a very long time. No question, some makes/models are inherently better-engineered than others. But upkeep (and how you drive it) are just as important and perhaps even more so. It’s not hard to prematurely kill even the best-engineered car by abusing it.

  2. What the oil companies don’t tell you is far more important than
    what they tell you. When a fire occurs in the cylinder of an engine, many nasty chemicals are produced including nitric acid,
    sulfuric acid, and hydrocloric acid. The mixture of nitric and
    hydrochloric acids is called aqua regia. It’s magic. While not a
    true chemical compound, it dissolves almost anything. As long as
    an engine is kept running the bad stuff is burned off or blown through; but when it is shut down, smoke is left in half of its
    cylinders, where the acids condense and eventually seep past the
    inactive piston rings and into the oil, which later carries it to all parts of the engine.

    “In the old days” people tried magnesium oil plugs and dip-sticks
    to neutralize the acids. These worked only until the corrosion film covered the active metal, which wasn’t very long at all.

    None of the oil manufacturers seem to say much about buffers
    or neutralizers or any other type of pH control.

    Practical advice: Use a moderately priced, moderately high
    quality synthetic or semi-synthetic; try to organize trips
    so as to avoid “short hops” or allowing the engine to cool significantly during errands; dump the acid, necesarily including the oil, according to the engine manufacturer’s
    recommended schedule for your type of driving.

    All of the oil manufacturers’ hype may be true; but it really
    isn’t pertinent to the foremost problem at hand.


  4. Thanks ” MIKE-K ” (great post above !)

    …. also, your general EPA study reference was a good lead. I didn’t yet find that 1976 study, but GOOGLE did locate a great factual 1996 EPA study on engine oil:


    Primary ‘conclusion’ of that Federal study on “Oil Change Intervals” (OCIs) was that:

    ” Oil change intervals can be extended beyond engine manufacturer’s warranty recommendations without oil degradation…” .

    Primary ‘recommendation’ of that study was that:

    ” …engine manufacturers extend the recommended oil drain interval…”

    That EPA study report is long & somewhat technical, based upon a very extensive test of primarily diesel engines. It’s about the only publicly-available OCI technical analysis I’ve ever come across.

    Some other points made in this study:

    – Automobile & Engine manufacturers specify “very conservative” {frequent} oil changes to minimize their potential warranty costs — and NOT based on any strictly objective analysis of oil and engine wear.

    – Normal oil filters only screen large abrasive particles (>20 microns), but do not otherwise clean the engine oil or control engine wear.
    Regular filters begin to plug when oil drain intervals exceed 18,000 miles. Oil in gasoline engines usually degrades due to water contamination and oxidation. Oil doesn’t wear out — it only gets dirty.

    – OCIs are mileage/months based primarily because of the simplicity in record keeping… although other vehicle use & maintenance factors are more important in determining proper OCIs. OCIs of 500 hours engine-operation-time on American cars are not unreasonable, depending upon useage.

    – Americans should be more aware of the ability to extend oil change intervals without engine wear.


  5. I had to laugh when I read Gail’s post. Years ago I was a tow truck driver. On the 101 in Santa Barbara I was called to a breakdown and when I arrived I discussed the problem with the lady driver. She told me that everything was fine until it slowed down so much she had to leave the freeway.

    I asked if there were any other indicators and she mentioned that the oil light had come on a few miles back. I did not laugh.

    As nicely as I could I told her to do both herself and her husband a great favor. I told her by no means tell her husband what she just told me, to tell him that the engine made funny noises and she pulled off the road and that as she was pulling over, the oil light came on.

    I figured the truth was only going to cause problems in the marriage and accomplish nothing. The damage was done and why exacerbate them?

    • Oh yeah!

      Years ago, I taught my wife (who is not a gearhead) a few basic things, including:

      If the “oil” light comes on or the gauge needle reads low (let alone zero) push in the clutch, or put it in neutral, immediately, then shut off the engine, pull off the road and call me.

      • “Oil light?”

        Kidding! I learned my lesson all those years ago. I wish I’d known of that little factoid BEFORE I burned up my engine …

        On the other hand, my pre-Queen car developed a computer glitch that had the Check Oil light flashing on and off at whim. Light goes on, I pull over immediately, check the oil, everything’s fine. Drive on, light comes on, I pull over, check the oil, and so on. Given my traumatic history regarding oil level, this had me BUGshit until a mechanic explained what it was.

        That was a 1986 Toyota Camry. It ran and ran and ran. I loved that car.

        • That’s usually the sender. It can go out on any car of any vintage.

          Had that go out on my parents’ car many years ago… but it got to me looking at the car where I found the trans drain plug was loose and leaking. Started thinking they had the trans wired to the same light… alas filling the trans did nothing as expected and the sender had to be replaced. Car was an ’86 mazda… wonder if the supplier in japan had a bad run of them 🙂

  6. I have a 2000 BMW 5-Series with 195k miles. I only use BMW synthetic and typically get 20-23k per oil change. The engine still performs as when new. The BMW synthetic is twice as expense or more than others, but I don’t mind dropping off only once a year for the service.

  7. Quote from an article in The Truth About Cars.

    In the mid-80’s, Germany’s leading car magazine Auto, Motor und Sport ran a VW Golf with a 1.6 liter gasoline engine for 100,000 kilometers (62,000 miles) without changing the motor oil or filter. They then tore down the engine completely and examined every single moving part [microscopically] for signs of wear and tear. What little wear they could find was not engine life threatening and fit within normal operating parameters for the given mileage.

  8. 87 toyota tercell, first oil change at 40k, 2nd at 95,000, after that not hardly at all. Traded it in with 207k and it still worked just fine. Maybe I was just lucky, or maybe the oil change trip is just mostly a scam.

      • Back in my shop days we had a car come in with 40k on the clock. Oil was never changed! Had a intake manifold gasket go out, or something. I don’t remember well. Anyhow, the lifter valley was all gummed up to shit and we ended up cleaning out what we could and charging the customer for a few oil changes in a row to get the sludge out. It is possible to do, I’ve seen it!

        • Back in the early 90’s I heard a coworker complaining that he only got 66,000 miles out of his Toyota minivan engine before it threw a rod through the block. I asked him how often he changed the oil. He said soemthing to the effect of “Oh I never bother with changing the oil, I just add some if it needs it.” Just goes to show you how tough a Toyota motor really is.

  9. I have a 2000 F350 with 370,000 plus miles on it. I change the oil and filter every 5,000 miles with Shell Rotella T.The fuel filter gets changed every 10,000 miles.
    I pull a 4 horse trailer with it on the weekends and drive it back and forth on barn calls during the week.
    Bottom line is that it still runs like a top and it doesn’t use any oil. I’ve done the same to each truck I’ve owned since 1980 and manage to get 400 to 450 thousand miles on the engines before I finally sell them due to the body and interior wearing out.
    Our Expeditions has 90,000 miles and we do the same protocols.

    • I do the same with my to Nissan Frontiers and have done similar in the past with other vehicles with excellent results. Like you, I end up with body issues long before I have engine issues!

  10. In regards to P.M. Lawrence’s comment about Trabants and Wartburgs in Germany: Yes, they are legal to drive in Germany if they pass TÜV and ASU – the safety and smog requirements for the year they were produced. There are still some driven daily (mostly Trabants) in the Former East but mostly for very short trips.
    After the Wall fell, the Trabant was fitted with a VW Polo (water cooled four-stroke) but this proved to be a token effort to continue production since it was a terrible car compared to Western competition.
    I imported a 1988 Trabant into the US in 1990 and kept it for 11 years. It got horrible fuel economy for a 26 PS car and gave me some problems because of its lack of compression. It was great as a piece of Communist History but sucked as a means of transportation.

  11. I take the guesswork out of the “how long to run this oil” by sending it for analysis every time:

    Blackstone Labs

    They run a comprehensive metals analysis, telling you if you’ve got valvetrain, cylinder wall, bearing, seal, piston ring, etc. material in your oil. For an extra ten bucks, they’ll run a “TBN”–total base number, which indicates how much life is left in the oil. Lastly, you get viscosity-at-temperature and fuel content numbers.

    They’re super people and send a brief summary with each analysis; they’ll tell you how much life was left in the oil and warn you if you’ve over-shot.

    It’s this analysis that moved me off Mobil 1 and onto Royal Purple. Mobil 1 used to give me barely 6000 miles in my wife’s car; I’m pushing 11,000 now with Royal Purple and Blackstone keeps encouraging me to go further.

    OTOH my M5 destroys engine oil–because it’s used much more aggressively than the Infiniti. Only the analysis would tell me that–not guesswork.

    It’s $25 a pop, 35 if you get the TBN number. You don’t have to do it every time, but the first couple will tell you where you ACTUALLY stand.

    • I never heard of such a thing as getting your engine oil analyzed by a company like Blackstone Labs. It’s cool to know about, and I have a geeky interest in getting it done, but my Mazda dealership changes my oil and filter for under $30 – so for barely more than the cost of testing the oil I can just get it changed.

  12. It wouldn’t be difficult for car manufacturers to run long-term, real-world tests of their cars with a wide range of oil-change-intervals — and then strip down those engines for factual comparison of change interval effects.

    Surely that’s been done many times over the past 50 years… that’s part of basic automotive engineering (??)

    If it has been done — the car manufacturers sure have kept it secret from the public. The internet should be full of such hard data– but it ain’t.

    The ‘better-safe-than-sorry’ approach to frequent oil-changes is very expensive overall, considering the gazillions of cars on the road. It costs the car manufacturers nothing to recommend unnecessarily frequent oil changes… and their dealerships do ‘sell’ oil changes for profit. Ask a barber if you need a haircut — and you will get only one answer (YES).

    Also, some car manufacturers admit officially recommending lighter-weight oils… to slightly increase the MPG on some vehicles (via reduced engine friction) — purely to meet stricter government MPG rules.
    (..possible increased wear on the engines was considered an “acceptable” tradeoff)

    Car manufacturers never say exactly HOW they determined their recommended oil-change intervals, or type oil. It’s heavily subjective, at best.

    • It’s been done through oil analysis. There are few ‘geeks’ out there on this topic. I believe that bobistheoilguy.com is their internet hangout.

      Anyway if you do oil analysis you can find the ideal interval for your car, driving style, and wallet.

      • Can you get the oil for sampling without changing the oil?

        Do you just get oil when you do an oil change and see if you extend/reduce the change interval?

        • I collect it at change time, but there are kits that let you slurp some up through the dipstick tube…assuming you have one! (Some not-to-be-named marquees today don’t)

    • In fact, the EPA did engine longevity studies in 1976 that very definitively charted engine wear across oil change intervals. Those studies also charted oil filtration quality against engine wear. I know of these studies only because I used to sell bypass oil filters. I’d hand those studies to prospective buyers, which made the sale a lot easier.

      The most notable finding was that, under ‘normal’ driving conditions (where oil temperature wasn’t pushed beyond the oil’s ratings… as would occur by racing, etc.), the oil filter was more important than the quality of oil. In other words, a high qualtiy (10 micron or less) filter (such as a K&N) extended engine life many fold over the use of typical 30 to 40 micron OEM quality filter.

      The studies showed that synthetic oil (over a ‘good’ qualtiy conventional oil, such as a Valvoline) provided little influence in extending engine life (assuming ‘normal’ driving conditions… not racing, or dusty off-road driving, etc.). The point is, removing particles (through filtration) dictated engine life more that ANY oil would.

      Now, because I sold these bypass oil filters (which filtered to 2 micron), I’d change my bypass filter and OEM engine filter every 10k and my 10-30w Valvoline engine oil every 30k miles. Because we owned an oil analysis machine, I’d analyze the oil every 5k or so (sometimes more) just to chart things. It got boring cause the oil, consistently, came back as ‘new’. It never loaded-up, so it’s additives never really depleated. There would be a reduction in viscosity (it would drop from a 10-30w to about a 10-25w due to mechanical ‘wear’ on the molecle length… which dictates the ‘w’ specs). The only reason I’d change the oil was because, emotionally, I just couldn’t stand it anymore. I’d just do it, even thought ‘scientifically’ that oil was still like new.

      So, in the end, the 1976 EPA studies showed conventional oil with a 40 micron filter enabled a 390ci V8 to go about 150k miles before meaningful wear resulted. Same setup, but with a 30 micron filter (Purolator, etc), would go 250k. Dropping the filtration to 20micron (which was the WIX filters at that time) would provide about 400k of life to that engine. And a 10 micron (which now-a-days is the K&N) pushed engine life to 700k. Using a bypass filter (like Amsoil or the one I sold was OilGuard) along with a 30 micron OEM filter, got 1.1 million miles (or better!) out of that engine before ‘meaningful’ wear occured. BTW… talk about over-kill… who’d want to keep their car for a million miles! But, for those of us who appreciate fine machinery, spending the $500 for a bypass filter setup helped us sleep at night.

      I know the oil officianodos are gonna pounce all over me for my claims here. I’m sorry to say I’m too lazy to locate those stuides and provide the link. They’re out there somewhere though. But, understand that I’m an oil ‘nut’ and would NEVER abuse fine machinery by treating it badly. So, please believe me when I say it’s all about the filtration, not the oil. Synthetic is nice stuff, and is a very loving thing to do to your car. But, the science says removing the particulates (via a 20micron or better filter) yields far more engine life with a conventional oil than can be had from any synthetic oil when using an OEM quality oil filter of 30 micron or higher.

      • Thanks for all this info, Mike.

        I certainly agree on the value of high-quality filters – they’re all I use. But I’d be reluctant (like you!) to push the oil change intervals to those extremes in other than experimental conditions and using someone else’s engine for the experiment!

      • Did anyone tear down these engines to see how much sludge formed? As I understand it, conventional oil has mostly the molecules desired for lubrication but much that isn’t as good or as durable. That part of the oil breaks down and becomes sludge over time from heat and wear.

        I can understand the part that remains circulating still being in good shape and clean with a good filter, it’s the part that becomes sludge that synthetic prevents. Also it doesn’t break down when subjected to that occasional high rpm usage 😉

          • Frankly, I haven’t seen ‘sludge’ in an engine since my teenage years when I’d buy a car for $50. Honestly, I just can’t imagine coming across any engine with a true sludge problem now-a-days. Sludge is, well… oil that’s so oxidized its essentially varnish. Varnish is an 1850’s invention where they’d litterally boil oil (which occurs at 400 deg F). Boiling simply extends the length of the molecule, which makes it less viscous.

            Motor oils all have detergents in them that keeps those lengthy molecules from grouping. They’re still in the oil, they’re just dispersed. No filter can trap them.

            Synthetic oil was developed in 1938 by the Germans to enable their tanks to start in Russia at -40F!!! The protective properties of synthetic(under ‘normal’ driving conditions)is only evident on the extremes: they’re more viscous at low and retain their rated vicosity at higher temps than conventional oil.

            Synthetics also boil at a higher temperature. A dino-juice Valvoline boils at about 410 deg F. While a synthetic Amsoil boils at about 440 F, and Royal Purple at 450 F. Unless you live in truly cold climates, or tow maximum loads at high speed (or loan your car to a 16 year old), your engine just won’t experience those extreme temps.

            Both conventional oil and synthetics have the same additive counts in them. So, each will deplete at the same rate. My experience with oil analysis showed that the oil’s additives (either type) were depleted by only about 5% after 3 to 5k miles of normal driving. My truck used a bypass filter, which I’d change every 10k, the conventional oil every 30k. The analysis showed my valvoline’s additives were only down by about 15% after 30k.

            When you push away all the rumors and predjudices about engine oil, the science shows its truly about filtration. Only folks in really tough winter condtions, or towing/racing condtions get value from a synthetic. For the rest of us, a good quality conventional oil, with a 20 micron OEM filter (no need to invest in a bypass filter setup) will get 4 times the engine life, and will only need to change the filter every 7500k (the oil every 21k would be fine).

            Please believe me when I say I’m an oil ‘nut’. And highly appreciative of fine machinery. I’d never abuse my engine. My advice is solid. For normal driving, it’s ONLY about filtration. It’s not about the oil. If it helps you sleep at night, use a synthetic. But, bang for the buck (and 4 times the engine life), just put an extra $5 into getting a higher quality oil filter and use a good name conventional oil.

            The ‘best’ OEM filter is the K&N(most filter to 10 micron). WIX and a few other ‘premium’ names filter to 20 Micron (which is still good stuff). Just don’t buy a cheapy Fram, they’re at 40 micron.

  13. Eric,

    What do you make of this:

    This spring I purchased a 2011 Hyundai Sonato 2.0T (turbo) new. The book clearly recommends I use 5W-40 for best performance. The book also says that if 5W-40 is unavailable I can use 5W-30.

    Now I use full synthetic oil in all my vehicles. If a manufacturer advises me to use 5W-20 I do… if the advice is to use 5W-30 I do… and so of course with my Hyundai I use 5W-40.

    I’m cheap, so I buy my synthetic oil at Walmart and my K&N filters at AutoZone or Advanced Auto. Upon getting my first oil change – at the Hyundai dealership – I found out that had I not brought my own 5W-40 (full synthetic) the dealer would have used 5W-30 – conventional or synthetic depending upon my instruction.

    Turns out that’s their SOP. (And btw… I later found out that some Hyundai dealerships use 5W-20 – not 5W-30 let alone the correct 5W-40!)

    Turns out that according to my three Hyundai tri-state dealership “survey,” dealers are not aware that the turbo Sonata should be filled with 5W-40 and beyond this… they just don’t care.

    Amazingly… neither does Hyundai corporate!

    Nor does Hyundai corporate seem concerned that while the owner’s manual recommendation is to use 5W-40 the factory engine oil cap indicates that 5W-30 should be used… and.. to reiterate… beyond this contradictions… Hyundai corporate doesn’t seem too concerned that some of their dealerships (same geographic region; same weather and road driving conditions) use 5W-20 rather than the recommended 5W-40 or “acceptable” 5W-30.

    I’m really, really, really curious as to what you make of this.


    • I think the key thing here is the language you mention. You note that the manual recommends 5W-40 “for best performance” but that you can use 5W-30. In other words, both viscosities are ok, but the 5W-40 is better. You won’t damage your engine – or imperil your warranty coverage – by using (or having the dealer use) 5W-30. The 5W-40, however, is probably what you want to use in your turbo engine due to the “40” part of the formulation.

      Hyundai corporate should have clarified this for you if the dealer could not or would not.

    • My 2 cents.

      The 40 weight in the 5w40 is because of the increased pressure put on the rings by the turbo.

      Years ago as a truck driver the company insisted they would only pay for Delo 100 (30 weight), and of course never understood why the trucks used so much oil and the rings/cylinders were failing.

      They finally got the word that the manufacturers recommended Delo 400 (15w40) they were supposed to be using would stick to the rings better under all that pressure and problem solved.

      Another case of penny wise- pound foolish.

  14. … endless “opinions” about proper oil & oil change intervals, but almost zero facts.

    I’ve never seen hard evidence of any consumer automobile damaged by exceeding manufacturer’s recommended oil change interval.

    Changing the oil/filter once or twice per year is probably good enough for most people, under normal American driving conditions (~2,000 -15,000 miles per year).

    Few people drive cars with 150,000+ miles on the engine… and even with those… there is no documented proof of engine damage or ‘reduced engine life’ due to extended oil change intervals. (Heavy use commercial/industrial vehicles are a different story).

    I’ve known a couple of people who never changed their oil — and their cars ran fine for the 5-6 years they owned’em. They just topped off the oil when it got low.
    I wouldn’t recommend that approach– but it indicated that oil changes are not an absolutely ‘critical’ maintenance item all the time…. and that the recommended change intervals are very subjective.

    This whole oil change issue is way over-hyped.

    • You can certainly make that argument and I have no doubt (because I’ve seen it) that engines (and machinery in general) will often survive incredibly abusive conditions.

      But my position on this is, why subject an expensive piece of machinery to anything that might constitute abusive conditions if you can avoid it? Especially if the cost of avoiding it is minimal? Almost anyone who isn’t physically incapacitated can change a car’s oil and filter themselves in 30 minutes for about $30 or so.

      The bottom line is I would not go beyond the factory recommended changeout intervals as they apply to my particular situation. Not based on the “best-case” situation that’s typically touted. Many people do not drive their cars “normally” as defined by the manufacturers. Many people drive under “severe” or “heavy duty” conditions as defined by the manufacturers. It’s important to read the factory recommendations as they apply to your particular situation and abide by them.

      Just my 50.

    • So instead of the engines lasting 30 years or so, they will die with the next owner.

      Take any used oil filter (full) and weigh it against a new filter (also full). The old one weighs more as it is full of contaminants. Soon the old filters clog or nearly clog and the oil just bypasses the element and the filter does nothing.

      Bad Idea.

      • Yup!

        Most oil filters (or the engine itself) will also have a bypass or pressure relief valve which will bypass the (clogged up) oil filter, so you get zero filtration.

        Modern engines are built to a very high standard and so can take a lot of abuse. But why would anyone want to abuse their engine?

        It just doesn’t click for me…

  15. Once upon a time when I was a cute young thing with the car-care awareness of an orangutan, I was tooling down the street when a thunderously loud !!!BANG!!! came from somewhere underneath, and the car died.

    I told my Big Bang story to the tow truck guy. He checked the dipstick — it was bone dry — and said, “Lady, do you ever add oil to this thing?”

    I said, “Oil?”

    He said, “Honey, you are now the owner of a 1500-pound paperweight.”

    Ever since, I am *rabid* on the subject of oil. I’ve always assumed that a good mainstream brand was acceptable and never thought about synthetics. Thanks for the education, Eric. Since the elegant and beautiful Queen is now 20 years old, she needs the best that the mind of man can contrive.

    • yup!

      One bit of advice I give people is to always check the oil level after it’s been changed by someone else, especially one of those “quick lube” places. It is not unknown for these places to put too much – or too little – oil in the engine.

      Never trust. Always verify.

      • You should even be suspicious of the dealership’s service department. My mom bought a brand new Toyota Starlet years ago. She took it back to the dealer religiously for all of it’s manufacturer’s recommended service intervals. At one point they changed the transmission lube (it was a manual) and didn’t bother to tighten the drain plug. Less than 10K miles later, the tranny drained itself and gave up the ghost. Of course the Toyota dealer disavowed all knowledge and responsibility. She informed them that the car had never been anywhere but there for service. They told her they had no way of knowing that, so it was her problem.

      • Additionally, always check your tire air pressure after they service your vehicle for anything. My Dodge Ram Diesel pickup has tires that require 80 PSI. Yes, eighty. Invariably, some well-meaning grease-monkey lets the air out of all 4 of my tires to bring them down to what he THINKS is the standard 35 psi. Verify!

  16. You don’t want gas in your oil – and only draining it will get rid of it.

    Yes, you do want that, or more precisely the other way around – if the car has a two stroke engine with crank case scavenging, like the Trojan (though the oil may or may not be supplied separately). And you don’t have to drain it in those cars, it just goes out in the exhaust. The fact that there are other issues with that approach does not affect this.

    • Well, yeah – but there are no two-stroke production cars and haven’t been (in the West) in decades. I’m pretty sure that last street legal two-stroke “vehicle” had two wheels, not four… and that goes back to the early-mid 1980s, a quarter century ago!

      • Well, yes and no. Yes, at the moment there aren’t any production two stroke cars in the western world – apart from any older ones still around that are allowed to operate under grandfathering rules, as the Trabant and Wartburg were for quite a while after German re-unification; I think the latter still is, at any rate at special events. And no, that’s irrelevant to the point; you made a very general statement and I pointed out that it has exceptions. While that particular exception only serves to illustrate the point, as it really would be a quibble if that were all, it could very well happen that two stroke engines made a come back in the future – though those would be likely to use a different lubrication system anyway. After all, on the one hand there are continuing developments like Orbital‘s and a recent motor scooter that has successful double scavenging (first air, then mixture), and on the other hand the older approaches still offer trade-offs that might come back – I have been thinking about writing up using split single engine vehicles with gasifiers and separate lubrication for your SHTF vehicle thread of a while back. I really should get around to that.

        • That’s a long moment!

          I’m petty sure there hasn’t been a two-stroke production car built for sale in the US since the 1960s and probably not since the 1950s. I’d need to check to be sure. But in any event, the article was based on a discussion of what’s in service now – and within living memory.

          Should I also mention caveats for bias-ply tires? Steam power when discussing fuel systems? Mention mechanical brake caveats when discussing hydraulic brakes?


          Two strokes are part of automotive history, at least at this point. Maybe someone will figure out a way to make them smog-compliant and they’ll be in use again in something other than off-road motorcycles and outdoor power equipment.

          I hope so. I like two strokes. They’re simpler than four-strokes and produce more power per cc of displacement.

          • Perhaps I should clarify: I am in Australia, and I am from Britain. Two stroke powered cars are well within living memory for people like me, and some still do show up at events like rallies and so on. Maybe ten years ago there were still TV advertisements for Australian Yellow Pages that featured a Scotsman looking for a Goggomobil – and it was a big advertisement campaign. If that’s history, that’s living history.

            • Ah! Makes sense now…

              Over here, the only two-strokes you’ll find that aren’t antiques are on two wheels (off-road motorcycles) and in the back yard (chain saws, weed whackers, etc.)

              I have an old two-stroke street bike (Kawasaki S1 triple) and have found many of the parts I needed to restore it across the pond. Apparently, vintage two-stroke bikes are still very popular over there!

          • I clearly recall a girl in my rural Iowa high school class who had a 2-stroke Suzuki 4WD in 1977. I believe it used a motorcycle engine roughly 600cc or so. She liked it because “it was easy to park”.

  17. Doh! I’ve been using the Walmart Cheapo Deluxe oil forever. I have 450k+ on my Saturn, 250k on the El Camino, 120k on the 4Runner, 48k on the Electra Glide, 22k on the Yaris. Hope there isn’t a special spot in hell for those who use cheap oil! Seriously though, I change my oil a bit before 3k on everything except the bike (that gets changed more often). Only thing I put synthetic oil in is my six speed tranny on the bike. The only reason I do that is because the tranny cost me damn near 4k.

    • wallyworld oil is just the name brand oil of the month or year that won the contract to fill the wallworld bottles. Nothing wrong with it, just change it frequently.

      • Exactly what I figured. Not only do I change it often, but I also check under the hoods of all my vehicles fairly often (checking/smelling fluids included). One of the shops I used to work at used bulk oil and it was pretty much the same deal. Don’t get me wrong though, if I had a high dollar engine (race car or something) I would be running the best thing possible. I can see running the synthetic for twice the mileage instances. I think this is the norm now with most cars 5-7,500 intervals between changes.

    • I think you’re doing fine – except for the bike! It is air (and oil) cooled, right? If it is, a semi or full synthetic is a good choice because of the higher operating temps. The other issue – which probably doesn’t apply to your bike (Harley) – is operating range/type of use. I run Motul or other high-end full synthetic in my sport bike because the engine runs to 12,000 RPM and I run the bike to 150-plus every now and then. I want every extra margin of protection I can get!

    • Maybe I’m a bit off based and dated dom, as my last Harley was a 1986, with the EVO motor. You don’t want to use anything in a Harley but Harley Davidson oil. The rest of it, whether synthetic or not is too thin to lubricate the roller bearings between the connecting rods and crank. Those roller bearings are one of the reasons Harley’s tend to last about forever. If you want to see 60k- 80k out of your HOG I would seriously talk to your qualified Harley mechanic. Mine freaked years ago when I told him I was doing what you are!

      • Hi Rick. I do think you are right, but I am too cheap and really don’t mind if my engine hatches. Think I’m pushing 50k on the engine now. My unit needs higher compression and some head work to haul my big azz around in sixth gear. I’ll keep on keeping on with the wally world oil in the engine. No cheap stuff in the tranny though. Thanks for attempting to change my ways. Promise once I drop a few dollahs in the engine I’ll be singing a different tune.

        • Shoot, I meant that I need work done to the engine. It has not been done yet. I am just waiting for a reason to do it. If it hatches I have that reason. Engine currently is stock with a cam, carb, and ignition. Sadly underpowered still.

          • This is the HD, right?

            I’ve never worked on one, but the layout is probably similar to a Japanese twin. Have you looked into a high-compression/overbore kit? I did that to my Kz900, which originally had something like 8.2:1 CR and now has 10.75:1 (plus another 100 ccs). The bike was quick stock – high 12s, 130-plus on top. It’s much quicker now and still very docile/ridable. I think the stock hp was 82 and with the high-comp pistons and additional displacement (plus everything being “tight”) it’s now probably close to 100 hp, which is damn good for an air-cooled machine.

            I think I’ve read about bikes like yours pushing 130 hp and 100-plus lbs.-ft. of torque…

          • I found a shop down the street that will go through and overhaul the entire engine for $1,500. Which is pretty damn good I think. I’d have them just change out all bearings and wear parts. Then step up the compression to just below 9.5:1 and call it a day. The engine is kind of tired. But yeah, these guys are building 2 liter Vtwin pelting out 140hp now.

      • I suspect bikes are more sensitive to oil – both the engine and the transmission. A sport bike engine can routinely see 14,000 RPM or even more. An air-cooled engine runs hotter, putting more strain on the oil’s ability to maintain that vital film of protection between critical parts.

        I would personally never use other than synthetic – very high quality synthetic – in a sport bike engine and only the highest quality conventional oil in air-cooled bike.

        I’d also only use bike-specific formulations if the bike has a wet sump clutch. Car oil is not meant for wet sump clutches…

  18. My ’04 Acura TL will display a notice when it thinks oil change will be needed soon, and then when it is needed. Do you think the car’s computer is really analyzing some of the factors you mention above? Or is it basing the notices mostly on mileage? You may not know about my specific model, so feel free to speak generally, about most cars that display such notices.

    • Some of these systems are sensor (rather than mileage) based. The ones that can actually sample the oil, or which analyze driving patterns and flash the service light based on that rather than how many miles you’ve driven since the system was re-set do a good job of indicating when you ought to change the oil/filter based on your particular driving situation. The key of course is to find out whether your system is “dumb” (mileage based service reminder) or “smart” (actual sensors, etc. that monitor how you drive and so on). The owner’s manual may have this info. If not, call Acura via their 1-800 service line and ask!

  19. The most important thing you can do to extend the life of your engine is to faithfully change the oil regularly. I have a 2000 Mustang w/120k miles on it that I bought new. I use Valvoline synthetic and change it every 5k miles. It runs like a top.

    • My ’97 is closing in on 200K as is my dad’s ’99. Both on mobil 1. A friend recently went over 200K in her ’03? I don’t know what interval my dad or my friend uses. I’ve used a slightly extended (~7K) drain interval since it went out of warranty. Motorcraft filters always.

      On how the sensors work, this is what I found:

      It’s along the same lines that I thought it would be but considerably more detailed than I figured.

      • I only use synthetics; the highest quality (Royal Purple) in my old muscle car and motorcycles (Repsol, Motul). I use Mobil 1 in the trucks; also their synthetic lube in the gearboxes and axles – which I find results in noticeable improvement in cold-weather operation. I have 140k on my ’98 and it still pulls 14 inches of vacuum, does not consume any noticeable amount of oil and runs as well as it did eight years ago with half the mileage. I have noticed no degradation in performance, or feel, during that time. I doubt there’s much if any internal wear. I bet the engine has another 100k in it.

        • Mobil 1 is not a pure synthetic. A real synthetic oil starts life in a laboratory from a Group IV base stock where as Mobil 1 is developed from normal Group III dino oil. Although it is a high quality oil, it would be illegal to sell it in some other Countries as a pure synthetic.
          It was originally a real synthetic oil but lost a law suit to Castrol years ago when it sued that company for using a Group III base but labeling their product as a synthetic. After the loss, Mobil began using the cheaper Group III oils but continued to label Mobil 1 as a synthetic.

          • I have grown as tired of this mobil one issue as the folks over on bobistheoilguy apparently have.

            First there was no lawsuit. Mobil filed a complaint against Castrol with the appropriate section of the BBB for false advertising. There is no evidence that mobil ever switched. Mobil 1 went on allocation to customers after Katrina damaged the plant that made their base IV stock. These two things together seem to have formed the idea that mobil 1 is not a full/true/fully synthetic oil anymore and was switched to base III. Thing is, there is no proof of it other than ‘some guy on the internet’ says so.

            Nobody but mobil knows how much base III vs. base IV stock they use and they aren’t saying either way.

            Other rumors are mobil 1EP is still base IV or the opposite, mobil 1 is IV while EP is III… it’s just all rumor on top of rumor.

            I got tired of digging into it and finding no proof either way other than what I found regarding availability issues of mobil 1 when the base IV plant went down. So if you have something better I’ll read it.

          • I remember when Mobil 1 first came out and they said 25,000 miles between oil changes. Now they say to follow the auto manufacturers schedule for oil changes. They now have a 10,000 mile synthetic oil.
            I guess that I’ll stop using Mobil 1 because of the changes. Amsoil sure looks good.

          • The change to manufacturer intervals happened very early on. It was likely due to warranty issues between the manufacturer and mobil being sued. No matter how good an oil is it can’t fix a good number of manufacturing defects. If you want to keep your warranty then it’s changing the oil per the book regardless of what the people who make the oil say.

            Also, be aware that warranties require the API certification which amsoil often does not have.

        • I used nothing but Mobil 1 in my wife’s Bronco several years ago. One day on the way home from work the oil pump went out. She drove it, to our mechanic, for 20 minutes with zero oil pressure and it didn’t sieze up. No question it was the Mobil One.

          • In extreme environments such as very high heat (or extreme cold) synthetics really shine over non-synthetics. I’m partial to them because I have old stuff, air-cooled stuff and high-performance stuff. Also stuff that has to deal with weather that sometimes dips to below 0 (F) and can sail past 100 (F) in the same year.

            Maybe a conventional oil would be adequate, most of the time.

            But I’m willing to pay a little more for more than adequate, all of the time!


Please enter your comment!
Please enter your name here