Don’t Ever Do This….

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Owner’s manuals are like “Moby Dick” – we might have a copy someplace, but few of us ever made it through the whole thing. For those who didn’t, here’s a short list of things in the don’t do that! section you may have missed:


* Tow (or haul) more than the maximum-rated capacity – 

Ugly things can happen if you do. Examples include hitches/mounting points actually coming apart – and your load coming loose at 65 mph. Or overloaded brakes failing as you slog down a steep grade. Beds/trunks weighed down by whatever you’ve crammed in there can compress the rear suspension dangerously – creating an evil-handling, ready-to-wreck ride that you’ll regret ever having set in motion. And even if nothing immediately awful happens, you’re still placing extreme stress on your vehicle that will result in premature wear and tear of parts, which means they’ll likely need to be replaced sooner than they otherwise might have. Burning up a clutch, ruining a $2,000 transmission or blowing out your shocks/struts can end up costing you a lot more than what you would have spent to rent/borrow a vehicle with the capacity you needed.

Or just use yours – and make two trips with two smaller/lighter loads.

* Keep your 4WD in 4WD on dry, paved roads – 

If you have a truck or SUV with a part-time 4WD system, the majority of your on-street driving should be with the selector in 2WD (aka, rear wheel drive).  The other ranges –  4WD High and 4WD Low – are not intended for use on dry pavement. Or even wet pavement. Driving on smooth surfaces with 4WD engaged (and especially going around corners on smooth/even surfaces with 4WD engaged ) can damage your 4WD system and leave you facing costly repairs. 4WD High range should only be engaged when there is snow on the road – or you’ve left paved roads entirely. It is designed to operate on uneven surfaces. 4WD Low should never be used on paved roads unless they are covered with deep snow. Otherwise, save it for driving off-road, at low speed, through deep mud, sand or on a very rugged dirt trail. 2WD should be re-engaged as soon as you’re back on dry pavement/smooth roads. If your pick-up or SUV has a locking differential(s), be certain you only use it when the vehicle is moving forward or reversing – and not going around a corner. When cornering, the inside and outside wheels turn at different rates; the differential allows them do so without binding up. But when the differential’s locked, the axles can bind – even break – if the stresses are severe enough. If that happens, you’ll be stuck – and broke, too. Once you get the bill for the repairs… .

* Use a different weight (or grade) of oil than specified by the manufacturer – 

This is especially important with modern engines, because they are built with much closer tolerances than the engines of the past. Running a really heavy oil (say, 20W-50) in an engine designed to use 5W-30 can increase friction inside the engine, reduce fuel efficiency – and possibly even lead to more serious problems that may not be covered by your new car warranty. The same also goes for American Petroleum Institute (API) ratings. If, for example, your vehicle’s manufacturer says to only use oil with at least an SM rating (for improved oxidation resistance, protection against deposits and better low-temperature performance) and you cheap out by using a lower-performance SH/SG oil (for 1996 and older engines) you found after doing a clean-out of your garage, you not only risk possible engine trouble – you risk losing warranty coverage for any oil-related failure that occurs. (See for detailed info on API oil service categories.)

* Use your transmission (manual or automatic) to “park” the car – 

The proper way to park your vehicle is to engage the parking brake before releasing the foot brake or putting the vehicle in “Park” (automatic-equipped vehicles) or releasing the clutch with the transmission in gear (manual-equipped cars). This way, the parking brake holds the weight of the car – not the transmission. If you don’t do it this way, you risk breaking parts inside the transmission (expensive) or (less expensive, but annoying) finding it’s hard to get the shift lever out of “Park” when you want to get going again. People have become stuck this way – and had to call AAA. Or had to arm-wrestle with the shift linkage for awhile before they were able to free the car. It’s something that should never happen – because it’s totally preventable.

* Drive fast (or far) on a space-saver Mini spare – 

Many new cars come with temporary use only “mini-spares” designed for just that – temporary use only. It says exactly that on the sidewall. They are not designed to let you continue driving as you were before the flat; they’re designed only to let you keep on driving – at reduced speed and extra carefully – to the nearest service station. Most “minis” have warning labels that caution you not to exceed 55 mph or drive more than 100 miles before mounting a real tire. The warning label will also usually tell you that your car may “handle differently” (read: weirdly) and that braking performance will be reduced (read: you will need more time to stop safely). The idea is to limp along carefully to the tire store – grateful for any forward motion at all. Don’t push your luck – or expect a temporary-use-only “mini” to do what a normal tire can do.

* Use tap water to top off your radiator (or battery) – 

Tap water can have impurities in it that you may not be able to see with your naked eye but which are nonetheless bad news for your car’s cooling system. Unwanted chemical reactions can take place inside expensive-to-replace radiators and alloy engine parts, such as aluminum cylinder heads. If you need to top off your car’s cooling system, you should use distilled water only. It should be mixed in a 50-50 ratio with the appropriate anti-freeze (standard “green” or long-life “orange”). Never exceed 70 percent anti-freeze in the system. It’ll be a congealed, gloopy mess. And: If the engine is hot, top off the overflow reservoir – not the radiator itself (unless the vehicle has been sitting for at least a few hours and had time to cool down). If you do remove the radiator cap, always use a towel to cover the cap as you twist it off to avoid being scalded by escaping steam/coolant. If you’re stuck in the middle of nowhere and distilled water’s not available, bottled water’s a next-best thing: It’s at least filtered and should be more pure than ordinary tap water. But don’t ever use bubbly mineral water under any circumstances. If you have no choice and all that’s available is tap water, use it – but once you’re back in civilization,  have the entire system properly flushed and refilled with the correct ratio of anti-freeze and distilled water.

Throw it in the Woods?


  1. In Michigan, if you buy any car that’s older than 10 years old, you absolutely do NOT touch the parking brake unless you like being stranded and/or destroying the rear brakes. That’s just common knowledge up here. The only exceptions are well-maintained vehicles with standard transmissions, and even those have to be very carefully tested before regular use is attempted

  2. I have a little locally-made 4X4 which, surprisingly, does actually have a locking diff to go with it’s permanent 4WD.

    That’s right, you can’t turn the 4WD off; it’s always on.

    Once I let my father in law tow my boat up the ramp and across the boat yard. He’s getting on a bit and my distinct and explicit instructions to turn the locking diff off when he was off the ramp were ignored…

    Happily there’s quite a bit of loose gravel there and no damage occurred, but the screeching, scrubbing tyres were painful to watch as he tried a 4 point turn to line the boat up with it’s shelter.

  3. OK, for the most part, I REALLY enjoy your website. And maybe for townies who drive their cars or silly SUV’s to the office, to the mall, to the health club and then home again, your advice is sound. But for you “ignert” country folks who actually TAKE your vehicles through horrible amounts of snow, mud and punishment, chain them up, get them horribly stuck trying to get home – DON’T TAKE THE PARKING ADVICE.

    During severe winter-time duty, mechanical parking brakes suffer damage to the brake cables which will sooner or later render the POS inoperable, or worse, it will set but not release due to freezing overnight or bent brake cable housings. For real, disable or take the damn thing off before it causes you to burn up your rear brakes or leaves you stranded somewhere.


    • Thanks! And, I hadn’t heard that one before (about the parking brake seizing up.) I also live in the country – rural SW Virginia – and I have a couple of older trucks. Never had a problem with the cables seizing up, but I’m pretty OCD about maintenance!

  4. Holy smokes, I done almost all of these things!

    Haven’t exceeding towing limits, or used 4wd on the road though.

    I’ve been using different grade oils for a long time as well as using my tranny ‘park’ to park the vehicle.

    Does this mean I’m going to hell? j/k


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