Maintenance 101: Old Car Oil Change

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Everything changes – even oil changes. Not necessarily the procedure. But the oil you use.

Or rather, ought to be using.

If you happen to own an older vehicle.

Specifically, a vehicle with an engine that has a flat tappet camshaft. Which is – pretty much – every American car with a V8 engine made prior to the early 1980s (at which point, roller cams began to come online, first in cars like the Mustang GT and 5.0 LX of that era).

But what is a “flat tappet” camshaft?oil1

It’s actually not the camshaft, per se, that’s the important (in terms of this discussion). It is the tappets – the lifters that get tapped (well, pushed up and down) by the cam’s lobes as they rotate. The contact surface of these lifters is flat. One of the reasons – the chief reason – why flat tappets were thrown in the woods (retired) in favor of roller lifters is that roller lifters allow more aggressive cam lobe profiles due to the more favorable geometry. Instead of pushing up against the flat bottom of a flat-tappet lifter – which places increasing pressure/stress on the flat surface of the lifter’s bottom as the eccentrically shaped cam lobe rotates to its “pointy” end (peak lift) – the cam lobe in a roller lifter scenario contacts a nearly friction-free roller on the bottom of the lifter that allows much more aggressive cam profiles with much less pressure/stress (and friction) on the valvetrain.

Anyhow, the issue is that older engines with the flat-tappet layout require certain anti-friction additives in oil – zinc dialyldithiophophate, or ZDDP – to avoid rapid wear and premature failure of the valvetrain. The problem is that the ZDDP has been all-but-removed from most (if not all) commonly available/over-the-counter motor oils, in part because modern engines with roller-type camshafts don’t need ZDDP but chiefly for emissions-related reasons.label1

All engines – even (especially) brand new ones (during break-in) consume a little oil as they run; the byproducts of that consumed (burned) oil – including the additives, now in gaseous form – become part of the exhaust stream.

Before catalytic converters, which came online in 1975, this was ok. Well, it wasn’t a problem (other than the occasional puff of blue smoke). The gasses – and whatever they contained – went out the tailpipe and were no longer your problem. Since catalytic converters became mandatory standard equipment – and especially since federal emissions laws became downright Stalinist in the early 2000s – the ZDDP additives in the oil became a problem because they tended to accelerate the functional degradation of the catalytic converter. Which the feds now require the car companies to warranty for 10 years/100,000 miles. If the converter stops doing its converting before that time/mileage interval, the car company is on the hook for all or some of the replacement costs.

Lots of bucks on the table.

So the car companies pushed for – and got – major reductions in the ZDDP mixed in with commonly available engine oil. Which most people don’t have to sweat because most people do not own cars that are 30-plus years old.pour1

But if you are among the few who do own a car that’s 30-plus years old … well, you have a problem.

Or will – if you use off-the-shelf oil that lacks the necessary additives.

And it’s not just a wear and tear issue, either. Cars 30-plus years old tend to sit a lot because they’re usually not used for everyday driving. My ’76 Trans-Am is probably pretty typical in that I take it out once or twice a month and drive it for about half an hour or so each time. This keeps the miles low – and when not running, of course, there’s little wear and tear going on, ZDDP or no ZDDP.

But when it’s just sitting, condensation (moisture) forms inside the engine. Oil and water – not good. Also, older cars typically have carburetors and they tend to leak gas into the engine. Gas is a solvent. Washes the oil off metal surfaces that rub together.

Also not good.  drainpic

I use Amsoil Z-Rod oil in my old muscle car because it has the anti-friction additives (ZDDP) its engine needs (particularly because my engine has been modified with a more aggressive camshaft, which means more aggressive cam lobe profiles and more pressure/stress exerted on the lifter’s flat base) and also because the stuff is specifically formulated for engines that do a lot of sitting. It has corrosion inhibitors not found in over-the-counter “mainstream” oils – which, remember, are formulated for modern cars with roller-type camshafts and fuel-injected engines.

Now, there are other high-quality synthetics out there (Royal Purple, Mobil1) and you can buy a bottle of ZDDP additive to mix with them. But I like Amsoil because it does not require the purchase of additive – and because it is formulated for the usage (and non-usage) patterns typical of “retired” vintage vehicles. I also get away with changing the oil just once a year – due to the extended drain intervals Amsoil recommends – which ends up saving me money over the long haul.amsoil filter pic

Also because Amsoil sells high-performance filters to go with the oil. Beware cheap (and made in China) oil filters.

They even have filters for long out-of-production engines like the 455 in the Great Pumpkin!

Final tip: I always refill the individual quart containers with the old oil just drained. This lets me keep precise track of oil consumption since the last oil change. If your car usually uses say a quart of oil in between yearly oil changes and this oil change you discover you’ve only got enough old oil in the catch pan to fill up four (out six) of the quart bottles instead of the usual five or so… it’s pretty solid evidence your engine’s either developed a leak or it is using more oil, the latter indicative of a mechanical issue you’ll want to look into. Either way, you’ll have an early warning – to check the dipstick more frequently.

Which could save your classic car’s engine from an early (and unnecessary) demise.

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  1. I used STP oil treatment in a old motor. It’s inexpensive and contains zinc. I don’t think that I would use it in a motor that requires thin oil , because it is kind of thick.

  2. I have a 1989 Chevy Cavalier Z-24 convertible. It is a 2.8 V-6 The oil fill cap on the valve cover has SF/CC 5W30
    The dip stick has
    “USE ONLY SF 10110440 ENGINE OIL”
    When I look those up on line it says that the SF is obsolete but does not name
    a replacement.

    • It is increasingly harder to find SF/SG oil. My 84 Honda Shadow requires that rating. Sure you can buy the dealer oil at 5 bucks or more a quart, but I hugely dislike being robbed to buy oil that doesn’t have the esoteric additives which should demand a higher price. it was like the insult of buying unleaded gas. It costs the gasoline company more to make leaded gas than unleaded by the mere fact you had to inject lead into the gasoline during the refinement process. I distinctly remember regular unleaded being 5 or more cents a gallon higher than plain regular. Right now the only place, outside of a dealer, I can find SF/SG oil is at Dollar General. The 10w40 DG branded oil is rated SG and works fine in my bike. I, however, like an earlier poster stated change my oil religiously (every 2k miles) and I use a Napa Gold oil filter (made for them by WIX but is less expensive than the WIX equivalent).

      David Ward
      Memphis, Tennessee

  3. I’ve plenty of old engines (mostly Mopar) sitting around and use just plain old dinosaur oil in them, which I change religiously every 3000 miles. I figure that even if synthetic oils themselves last longer, the crud, water, and combustion byproducts in them that cannot be filtered out merit frequent change of oil anyway, so I might as well use the cheaper oil.

    But I have a question: is it still possible to wipe a cam in a well-used engine using low zddp, or is that only a problem with new (rebuilt) engines?

    • Hi Ross,

      Some claim it’s ok to use oils with low ZDDP in engines already broken in; others (me included) take the view that it’s probably sound policy to use oil with ZDDP in engines originally designed to use oil with ZDDP. The friction/pressure issue of the flat tappet layout remains the same even after break-in and I’d rather not chance a major engine problem.

      Now, if EPAutos had the resources to take a victim engine and experiment

  4. We use Shell Rotella for break-in on our race engines without issues. It’s a great budget alternative to dedicated break-in oil.

    For a street car that sees mild track use, a wix filter would be my choice combined with Valvoline or Mobil 1 Synthetic.

    A race car will get either a Wix Racing filter or Royal Purple filter. Royal Purple or Redline oils are my personal preferences for a track car.

    From what I’ve heard, modern engine oil additives are a sufficient replacement for ZDDP in Flat-Tappet applications. Everything API GF-4 certification is backwards compatible. Here is a snippet from an article I was able to dig up:

    “Each new API category has placed successively lower phosphorus and zinc limits, and thus has created a controversial issue of obsolescent oils needed for older engines, especially engines with sliding (flat/cleave) tappets. API, and ILSAC, which represents most of the worlds major automobile/engine manufactures, states API SM/ILSAC GF-4 is fully backwards compatible, and it is noted that one of the engine tests required for API SM, the Sequence IVA, is a sliding tappet design to test specifically for cam wear protection.”

    • Pedro, I can see running Rotella in some weight for racing engine break in oil. It’s good and cheap, an uncommon combination. I’d probably be tempted to run it through some really fine filter and use it for something else.

      But using the same Rotella T 15W 40 we use in trucks is wrong as far as I know about 5.3 and 6L GM gas engines. They call for much lighter oil. With a new one I’d most likely use the 0W 30 Amsoil or the new 5W 30. Only one vehicle I changed to Amsoil that didn’t use less oil and all of them it quietened.

      • Modern engines have a lot of small oil passages and need the right weight oil to make all the valve adjusting and other gizmos work right. I can see some small variances working but not large ones. The manufacturers have small differences between engines that are 90+% the same. Most modern engines hover around a 5W20 give or take it seems.

    • Controverial indeed. Lots of guys out there with wiped cams would say that the oil mfr. claims of the new oils being backward compatible is a load of crap. Can’t say I have ever wiped a cam but I use Valvolone VR-1 or supplement with ZDDP Plus. Maybe a broken in cam with low spring pressures and slow opening rates will live with the new oils. Something more racey (strictly talking flat tappet hydraulic cams), like the comp xe series or lunati voodoo, especially if it is high lift, will not last without at least 1200ppm zddp (not to mention proper break-in procedure). Lots of info available on the net for anyone interested.

      • Dbb, You have never had a wiped cam lobe, fair enough. Reckon it’s because you use premium oil and change it and the filter occasionally? To be honest, I’ve only experience a bad lobe one time and I inherited in a junkyard BBC. I notice a tick one day quickly after buying this truck so I pulled the valve cover and low and behold you could barely tell anything except big blobs of black almost solid oil bs. I was amazed and envisioned somebody who cranked this engine up and drove a few blocks and turned it off or something similar and NEVER changed the oil or filter. Not really wanting to pull the heads and do a head job I just started changing oil and filter every 1,000 miles or less, sometimes just several hundred miles and then the lobe got bad enough quickly to have a partial miss. Next time I pulled the valve covers, it was all clean and all that crud(several pounds probably)was gone along with the lobe.

        My dad, after I had test driven every small pickup made and bought a Nissan and told him to buy a Toyota like my smarter friend had done, bought an S-10, a raving POS. After a few years it developed the inevitable computer controlled carburetor nightmare. He took it to our cousin, the mechanic, who absolutely didn’t savvy any of it and repeatedly sprayed Chemtool into it while revving it way high. No matter how many cans of chemtool went into that carb it wasn’t going to be fixed. Then it gets really bad and I bring it to the house and without a fuel pressure gauge, simply try a new fuel pump(I’m getting there)since I could get one really cheap. I removed said fuel pump, stuck on the bottom of the engine, running off the crank I suppose and pulled out what resembled a piece of wood covered in used crankcase oil that had set for years in a puddle. I banged on it and finally could tell it had a spring. Eventually I got it clean enough to slightly resemble a stud and nut with a spring under it and what might be a chamber with a diaphragm in it. At that point installing a new fuel pump was no longer the agenda. I put it back in clean and surprisingly it did work a bit better….and that may have just been because I drove shit out of it. My dad could kill a vehicle faster than anyone I ever knew. He drove about 6 blocks(I would rarely have even used a car or motorized vehicle for that distance, commonly walked 30 blocks each way to work for a long time and it was only the really late night blowing snow and rain that bothered me). He’d do this several times a day to a vehicle and get the oil changed now and again.

        I tried to get it over to him that his cars and pickups needed new exhaust systems constantly because of that same phenomena. For whatever reason, he’d never just come out, let me jack it up and change the oil and filter I had on hand and it wouldn’t take but a few minutes with my air jack. Instead, they’d use the excuse to drive it 60 miles to the largest town and eat out, my mother’s mantra, and go by Jiffy Lube and have the oil changed. One Saturday evening, unannounced, as always, they show up, the gate is locked so they bitch because it’s locked. If I’d been smart I would have used a different lock. You lock your gate sometimes when you’re home simply because you don’t want company and this was one of those days. So he gets to the house and tells me his oil light came on when he stopped and he could hear it knocking. I asked how long it had been since the oil was changed and he said that afternoon at Jiffy Lube. After it sits 30 minutes I check the level, nada, zilch, nothing showing. I only have a couple quarts of oil like he used since I mainly used HD oil and was temporarily low since I purchased it in cases or 5 gallon buckets. I put in two quarts and it gets on the stick, still about a quart low. Good old Jiffy Lube, stuck two quarts in a five quart system. I still could not get him to come out and let me change oil and filter on a regular basis. You don’t have time my mother once said. Hell no, I don’t have ten minutes to change oil and filter but hours and hours to work on those malfunctioning POS. I could have talked to a fence post and got better response. There ain’t no fixin stupid and when it came to car maintenance, they were the epitome of it.

        And they were smart people. I finally got it over to my mother and she’d get on my dad over it but they never would simply let me service it. I had plenty of room for used oil so it didn’t put me out hardly at all, really not at all since I enjoyed the visit.

        And it mattered not where it got serviced, it wouldn’t have been done as well as what I did and I looked a lot of things over besides just changing the oil(and actually greasing it like others didn’t)and filter.

      • Agree, Dirtybob!

        Here’s my reasoning: Cam lobe as it comes off base circle and begins to “ramp up” places a lot of pressure on the lifter. Broken in or not, those cams/lifters were engineered on the assumption that high ZDDP oil would provide the necessary protection.

        To draw an analogy: Older cars with carbs were designed to burn 100 percent gasoline. Not 90 percent gasoline and 10 percent ethanol alcohol. Yes, they will run. But they run lean (and hot) because the A/F mixture on E10 is different than on pure/100 percent gas. Countermeasures are necessary – re-jetting. And some parts must be replaced with ethanol-compatible parts.

  5. Here at the VW shop we use Brad Penn oil on most air cooled VW’s, unless it’s a beater, then it gets conventional with some Redline ZDDP additive. All late model water cooled VW’s (and Audi’s) get Motul VW specific oil.

  6. Most oils designated for diesel service still has ZDDP. Having the anti-friction additive is critical in engines with reputations for wiping cam lobes. CRITICAL. Even industrial engines in tractors, skid steers and stationary power units. CRITICAL. Can not stress this enough!

    • That reminds me of a 58 Chevy my dad used to have. Bought it in 1970, w/I don’t know how many miles on it, but it was only $50 and the tires were worth more than that.
      When the fuel pump died, his local mechanic friend said “I don’t know why anyone put an electric fuel pump on that to begin with.” When he put on a new mechanical pump, he found out. The pump lobe on the cam was wiped.

    • I recall reading that most Rotella now has reduced zddp levels (roughly 900 ppm) and that the ‘good stuff’ is only available in 55 gallon drums. Need to look for a CI-4 rating (1200ppm + of zinc & phosphorus)
      I normally use Valvoline VR-1 for my flat tappet stuff…

      • DBB, I doubt that. The new Rotella T advertises Triple T Protection by ash reduction and wear additive increase for a 22% better wear factor compared to Cl-4 Plus. I’d find it hard to believe bulk oil would be different than the gallon to five gallon oil you use for make-up.

        • having some trouble posting replies so will try again with the hypertext links disabled…

          It seems I bought into some of the flap about zddp reduction in the newer CJ-4 Rotella. They did reduce the zddp but not below the ‘safe’ zone for hyd. flat tappet cams. Also “We still sell Rotella T 15w-40 CI-4 in 55 gallon drums, but not in smaller packages.” and

          Did some research on bobistheoilguy forums and found a voa (virgin oil analysis) for 15-40 CJ-4 Rotella that doesn’t quite jive with the posted email response on hotrodders forum.
          and a second one that doesn’t match well with the first….

          Also stumbled across this: “Diesel oil is engineered with a higher amount of dispersant and detergent package to deal with the increased amount of soot and other hydrocarbon combustion by-products present in a diesel engine. This high amount of detergent can increase the decomposition temperature of the ZDDP which will reduce its effectiveness as an anti-wear agent, especially when a vehicle is used for short trips and does not achieve a full warm-up condition.
          Diesel engines are engineered with this constraint in mind, unlike gasoline engines.”

          Not so sure I would run a diesel oil in a gas motor after reading that but my boss runs it in his (1980) Porsche track car without any issues so far.

    • I like Wix, Purolator, B-line. For anything I can get an Amsoil nan-tech filter for that’s what I use. I put a K&N air filter on my 6.5 Turbo when they were all the rage. First check I noticed on the wrong side. I cleaned it, re-oiled it and ran it a bit longer, dirt on the wrong side. I put in a Purolator with foam before pleated paper and no dirt. I eventually replaced that with a washable duel foam job from Amsoil, once again, no dirt. I still have the Purolator on stand-by. The K&N on my wife’s car keeps the inside clean. I noticed the one for my pickup was awfully thin. Since then I have replaced the filter on a couple other vehicles including a Tahoe with the Amsoil dual foam filters. They seem to be great. Purolators are good and the foam keeps a lot of dirt from reaching the paper and if no one had washable filters, I’d stay with them. I noticed no performance difference with any of these filters as K&N advertises.


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