Car care: Myths vs. reality

When it comes to maintaining your car, misconceptions abound. And even the best intentions can lead you to spend more money than necessary or even compromise your safety. Here are a few common car care myths that can do more harm than good.

Myth: Engine oil should be changed every 3,000 miles.

Reality: Despite what oil companies and quick-lube shops often claim, it’s usually not necessary. Stick to the service intervals in your car’s owner’s manual. Under normal driving conditions, most vehicles are designed to go 7,500 miles or more between oil changes. Changing oil more often doesn’t hurt the engine, but it can cost you a lot of extra money. Automakers often recommend 3,000-mile intervals for severe driving conditions, such as constant stop-and-go driving, frequent trailer-towing, mountainous terrain, or dusty conditions. Read how to check your car's engine oil.

Myth: Inflate tires to the pressure shown on the tire’s sidewall.

Reality: The pounds-per-square-inch figure on the side of the tire is the maximum pressure that the tire can safely hold, not the automaker’s recommended pressure, which provides the best balance of braking, handling, gas mileage, and ride comfort. That figure is usually found on a doorjamb sticker, in the glove box, or on the fuel-filler door. Perform a monthly pressure check when tires are cold or after the car has been parked for a few hours. See our tips on tire maintenance.

Myth: If regular-grade fuel is good, premium must be better.

Reality: Most vehicles run just fine on regular-grade (87 octane) fuel. Using premium in these cars won’t hurt, but it won’t improve performance, either. A higher-octane number simply means that the fuel is less prone to pre-ignition problems, so it’s often specified for hotter running, high-compression engines. So if your car is designed for 87-octane fuel, don’t waste money on premium. (Read more on how to get the best gas mileage.)

Myth: After a jump-start, your car will soon recharge the battery.

Reality: It could take hours of driving to restore a battery’s full charge, especially in the winter. That’s because power accessories, such as heated seats, draw so much electricity that in some cars the alternator has little left over to recharge a run-down battery. A “load test” at a service station can determine whether the battery can still hold a charge. If so, some hours on a battery charger might be needed to revive the battery to its full potential. (See our car battery ratings and buying advice.)

Myth: Let your engine warm up for several minutes before driving.

Reality: That might have been good advice for yesteryear’s cars but is less so today. Modern engines warm up more quickly when they’re driven. And the sooner they warm up, the sooner they reach maximum efficiency and deliver the best fuel economy and performance. But don’t rev the engine high over the first few miles while it’s warming up.

Myth: A dealership must perform regular maintenance to keep your car’s factory warranty valid.

Reality: As long as the maintenance items specified in the vehicle owner’s manual are performed on schedule, the work can be done at any auto-repair shop. If you’re knowledgeable, you can even do the work yourself. Just keep accurate records and receipts to back you up in case of a warranty dispute on a future repair.

For more on taking care of your car, see our guide to car maintenance.  Talk with others about car maintenance and repair in John's Tool Box forum.

Comments

[CyCarConsulting]

I disagree with your oil change intervals when relating to Japanese cars. The lubrication holes and valleys are way undersized for what they need to be. With this design flaw your only insurance from engine damage is frequent oil changes, not more than 3,000 mile intervals. Also depending on how you drive, and how long your car sits, will determine how much slime( the new term for old school sludge ) you will acquire in your oil pan.

Having worked for Toyota,and Honda and taken many trips through the service dept. I always stopped at the stations where the engines were on the ground. My question to the techs, why? Most of the time the same answer, they didn't change the oil enough.

We can argue this point for years with experts, and engineers, but I know what I've seen first hand ,just change the oil more frequently and have peace of mind, for pennies.

[everett whitney]

"7,500 Intervals" are Totally Improper For Many!

CyCarConsulting's Input is 'spot-on' for the Vast Majority of commuters that never take the vehicle out-on-the-Interstate for 45 minutes / an hour during those ~ 7,500 miles!

At the installed cost now for a rebuilt engine, there will NEVER be the offset in "halving" the frequency for the overwhelming numbers of cars that simply "go" a few miles to the bank / dropping off the school tribe / soccer & music practices, etc., all only amounting to 7 - 10 miles @ at time. Terrible duty cycle for these modern engines!

For those that actually need to save very diligently, even paying for an appropriate disposable waste container each time plus the ~ $10.50 for the gallon jug of Top brand oil + another ~$3-$4 / filter,there's No Savings in postponing the oil changing!

everett

[W Smith]

I have changed oil at 3,000, 5,000 and even 10000. Never had a problem. Owned Japanese autos, German autos and many American autos. I have had friends engines crash and in every case the dealers said it was the owners problem. It was never the fault of the manufacturer.? Unless the owner is a mechanic and tears down his own engine how would he know?

[Sam W. Keenon]

There is nothing wrong with changing oil at 3000 mile intervals, if it gives you peace of mind, but it surely isn't necessary. The builders of engines would never recommend an oil change frequency that would cause them warranty claims.
Modern engine oils do not wear out. Modern filters take out the fine metal particles that may accumulate in the oil.
Oil galleries are sized to maintain the proper oil pressure at the point of lubrication. The larger the gallery, the lower the pressure.
Change your oil at whatever milage suits you, but change the filter at each oil change.

[TGT]

Sam's first sentence is true, but irrelevant. There's nothing wrong with throwing money in a wishing well, if it gives you peace of mind that good things will occur, but it's still throwing away money.

Your peace of mind should be based on reality, not marketing and outdated information.

[ian]

"engines crash"? Engines don't "crash." They can fail in a bunch of different ways. Some can be due to neglecting maintenance, some can be due to incompetent maintenance, some can be due to environmental factors, some can be due to operator error, and some can be due to design or manufacturing defects.

Yes, there is something wrong with 3000 mile intervals. It is wasteful of both money and natural resources, and depending how scrupulously the oil is handled, it can be a source of environmental pollution as well.

Unless there's something wrong with your car (overheating, particularly), you're a leadfoot, you're using additives like seafoam (which shouldn't be routine), or you've contaminated the oil in some other way, it should never be necessary to change your oil at 3000 miles. Modern oil, even in old engines, is just better than that. Click and Clack recommend 5000 miles. This is consistent with my experience, that oil usually starts looking less transparent, and having lower viscosity around that time. And that is when you should change your oil...when it stops looking like it did when you put it in the car. It might be longer in cars designed for high intervals, using expensive synthetic oil. (If it looks like chocolate syrup, you've waited too long...and BTW it won't taste like chocolate syrup.)

And while a battery may not be fully charged in a short drive, 20 or 30 minutes of driving will pretty much charge the battery enough to start the car again next time (assuming the alternator and battery are in working order). Considering almost every time I've jump started a car has been at around -50F, I don't think cold is going to change this.

Also on the subject of cold: you aren't just warming up the engine, you're warming the transmission. This isn't a big deal when it's +40F, but it could be at -40. It's also absolutely mandatory in many carburated (so nothing after 1991) vehicles at those temperatures.

[Meggeler]

I recently bought a new car. As an ancillary dealer purchase I bought service for 60k. The 60k package included oil changes at 5k intervals. The dealers service department sent me an email about my first 3k service???

In the past I change oil at 3k, but I decided to change to 5k - seemed the people who sold me the package should know something - well, I'm sure they are sales people also selling cookware - so, what I to do? Lose 40% of my package or change oil at 5k rather than 3k.

[techphets]

The suggestion about not warming up a car for a few minutes bugs me. Engine components change shape as they warm up. When those components reach operating temperature they have also expanded to the dimensions which the engine was designed around.

The factors to be concerned with aren't if the engine has reached maximum efficiency and deliver better fuel economy (don't these go hand in hand in the first place?). What is important is if the engine components are being stressed when they have not yet warmed up.

Sure, driving the car may warm it up faster but the internal engine components are also going to be under more stress!

[Bradley]

Anecdotal evidence isn't evidence, but here's mine anyway.
I change the oil on my cars at anywhere between 8 and 10000 miles, and I have never had an oil related problem on any of my cars. Including mt Toyota Pickup with 365,000 miles and my Saturn SL with 170,000 miles. Although not driving like a maniac probably has a lot to do with it too.

[Michael]

In the days of carburetors and early throttle body based top ends, you needed the engine warm to get proper fuel pressure. With these same older generation of vehicles, the piston rings tend to wear out a bit faster so that is when they recommended oil changes at 3000 miles. Those were also vehicles where it was common to see engines die or need full rebuild around 80-100,000 miles. It was not uncommon to see partial for full engine rebuilds needed in this time frame.

About 10 years ago, a mechanic friend of mine who rebuilt the 360 V8 in his 1975 Dodge truck every 100,000 miles due to the smoking, seals, piston rings and everything else giving out, finally decided to put the money into something else... so rather than trash the truck or buy a new one, he simply swapped out the engine with a much newer 318 Dodge/Chrysler crate engine (exact same setup in the newer 5.7L Hemi engines) except he kept the carburetor. He did add a basic computer for a few sensors but otherwise it was a new engine setup in an old truck. That same engine, with oil changes very close to every 5,000 miles currently has 412,000 miles and never been rebuilt. The body of the truck is somewhere over 1 Million miles (although not verifiable by paperwork or the 5 digit odometer).

With new generations of vehicles on the road, anything that has been made since the early 90s can go 5000+ miles between changes without a problem. The main people behind the current "3000 mile suggestion" are those who benefit from it the most (big oil), or those who have not updated their knowledge about newer vehicles. The oil in my 2004 Dodge Durango looks the same after 5,000 miles than it does when I put it in fresh, but I do the oil change anyways....

[rc]

@CyCarConsulting Just another reason not to buy Japanese cars. I was surprised when I discovered a brand new Honda I bought required oil changes at 3750 miles and ran regular oil rather than synthetic. My Mercedes runs Mobil 1 synthetic and with its Flexible service system is able to go 15k on an oil change. With no service loaners and stupidly frequent oil change intervals I no longer own the Honda. Ironically as well the much larger and heavier 6cyl powered Mercedes gets the same fuel economy as the 4cyl Honda and has 230hp rather than 150hp. The Japanese car makers build their cars around a price tag. Synthetic oil is expensive and they can save about $50 a car by putting in regular oil. You get what you pay for. My Mercedes has 480k on its original Engine and transmission and is still an absolute pleasure to drive.

[rc]

@techphets Older cars had carburetors and non electronic ignition. The warm up was required to keep these engines from just stalling out. Newer cars have fuel injection and computers that compensate for air temperature, engine temperature and run time. You are right about the engine components changing shape but modern cars are not F1 cars that have really tight tolerances. F1 cars have to be "heated" before they can even be started because of these tolerances. Modern cars have cold start tolerances and computing to adjust the fuel to air mixture to make them run optimally from the second the engine comes to life. Unless you drive a vintage car with carburetors or an F1 car the warm up cycle is taken care of by the engine's computer.

One thing to consider however is the first mile of driving. This is where the transmission and brakes get their warm up. As long as your gentle with the car for the first mile or so all the systems are pretty much at their optimal operating temperature.

[Scott]

I've run several Japanese cars to 200,000+ miles changing the oil every 5000 miles -- without engine problems. It's not just about money, it's also about conserving resources and making decisions based on facts, not emotions or old habits. I know many people who still insist on buying premium fuel for their low-compression engines even though it's been proven that it offers no benefit for the extra money.

[Bruce]

So you think because "your neighbor" or "best buddy" rebuilt his engine (or even a couple) that makes them an expert??
I'm an ASE Certified Master Engine Machinist (have been since the ASE process first started) and have spent more than 40 years in the engine rebuilding field. Had my own engine shop for 18 years. I have torn down and rebuilt hundreds, heck probably thousands of all types of engines!
The biggest cause for failure I have seen is STUCK OIL RINGS causing the engine to use excessive oil. This is usually caused by excessive oil change intervals allowing the oil to become contaminated with more than the oil filter can handle. Now newer engines DO have a better reputation for milage but the oil is better now too.
Motor oil is a VERY slippery subject,,ask 10 men about motor oil and you will very likely get 10 different answers!
What do I use in MY stuff?? I switched to Synthetic in everything I own more than 20 years ago (Mobil One).One thing synthetic does (besides giving better mileage and easy cold starting) is KEEPING YOUR MOTOR CLEAN. It's virtually impossible to sludge up a motor on Synth oil,, even if you ran it at room temprature!
I have taken apart engines that have run Synth oil (usually due to gasket problems but THAT'S another story!!) and they are UNBELIEVABLELY CLEAN!!
Now Synth oil might NOT make sense if you have an older car that's using oil. But for a VAST majority it's that way to go.
Oh yeah,, I change my Synth oil every 7500-9000 miles.
But HEY,,, that's just ME!!

[Damien]

The tyre 'myth' isn't quite accurate either. Manufacturers usually quote a conservative figure since lower tyre pressure means a smoother ride. The figure on the placard is acceptable, but putting another 3-4psi in your tyres will improve wear and handling.

[Car guy]

The amount of complete garbage posted by commenters on this article is astonishing.

Yes, anecdotal evidence is always more impressive and accurate than that provided by certified engineers.

[Dean]

As a former mechanic at the GM desert proving ground,ALWAY'S go by the door sticker for tire pressure! Say you go to the local tire store for tire's for your Impala.The guy behind you buy's the same tire's for his pickup.HUGE load difference!
Over inflate tire's for better handling? Nope! You will slightly increase the diameter and maybe get fractional mileage increase,but by over inflating,you reduce the "contact patch",or the tread on the road,and reduce handling.

[Matt]

Myth #1 (oil change) - No

This is entirely dependent on how far and how you drive. I have changed my oil after 2k, because I was hauling a 8000lb trailer around. I could see that the oil was filthy black, not the deep golden carmel color (presupposes that you have no other leaks internally...) The farthest I've gone is 5k, and could have gone longer, but the oil had been in my truck for 6 mos. I see few comments on low mileage driving here. Changing oil at the 7500 mark, at an interval over 6 mos, is just stupid. If you can't afford 2 oil changes a year, don't own a vehicle.

Myth #5 (Warmup) - No

You should let your vehicle "warmup" for at least say 20 seconds. Although, warmup would be a misnomer for this, call it fluid distribution. Oil and tranny fluid should be allowed to be circulated for a few seconds before punching the throttle like some folks do. I also let my truck move at almost idle for the first 50ft. Gives the cold thick lubricants a chance to move to where they need to be, before putting stress on the metal to metal contacts.

[Tom G]

The thing that jumps out to me is that how often do we really hear about wear related engine failure in a car? Not much. when a car experiances catastrophic engine failure there is usally an identifyable cause other than "didn't change the oil regularly enough" ZIt's usually due to lack of fluids. Not checking fluid levels. I've owned alot of cars and haven't junked one because of engine failre. It's usually something chsis related or maintenace and repairs that cost more than the value of the car.

[Matt]

Bruce said: Motor oil is a VERY slippery subject?! I had to giggle when I read that. I'm surprised that comment wasn't made much, much sooner. Thanks for injecting a little fun into my day.

[Mike]

3000 miles is right for an oil change, unless you use synthetic, then you can go 7500-10,000 miles. (I work for the plant that makes and bottles Mobil 1 synthetic.)

The bypass in the oil adapter is set at 30psi anyway, so most of your engine oil is NOT getting filtered, but merely bypasses it. If you remove the adapter, and plug the bypass valve, ALL the oil gets filtered. This requires a filter body that will not burst. Fram makes a line of burst-resistant filters.

Also, Bruce made very good points. Synthetic oil is well worth the investment. And, on a new car, synthetic trans fluid is worth the money too. The fluid will not burn like regular fluid, and the trans lasts longer.

[Mike]

Oh, another thing about the oil. Since carbs went the way of the dodo, and more accurate fuel injection has become the norm, engine oil experiences less gasoline contamination. Improper fuel/air ratio can contribute to gasoline thinning the oil.

[woody smith]

From the UK I am really puzzled. The recommended change on my Diesel Ford Focus is 12,500 miles as was the Diesel Honda Accord I had previously, which I had for 100,000 miles and nothing ever went wrong with it, not once. I have a collegue who has a petrol Vauxhall (GM) Insignia and the Oil change interval is 20,000 miles. Why are the intervals so short in the US?

[Gordon]

I do my oil change intervals at 10K miles. But I am using synthetic oil (Mobil 1). I had built up to this mileage by starting at 5k miles. I had the oil analyzed and the company doing the test said the oil was just fine and to go ahead and change the oil at longer intervals. But I had the oil checked again because I had wanted to see how the results are when driving during the dusty summer months. Again the results were good. I bumped the oil change interval to 7.5k miles and did it twice to see if seasonal weather conditions affected the oil. Tests results were good again. Finally I went to 10k miles and had the oil tested and everything is just fine.In fact they said I could extend the interval. Now I have 310,000 miles on my 4-Runner and it runs very good. The oil gets darker but it is still transparent unlike regular oil which gets rather murky. It took me just under two years to reach the 10k change interval.

[MikeH]

I have an old carbureted car (1965 Chevy Corvair) and you don't NEED to warm it up before driving. It, and most other 60's plus cars, had automatic chokes that would keep the engine running until it warmed up. It's not as reliable as modern fuel injection of course but there's no need to run the thing in the driveway. Plus, I've tried warming my cars up without driving them to do oil changes and it takes a long time for them to warm up just idling.

By the way, the Corvair had a very specific tire pressure requirement from the manufacturer. If you failed to observe it, you could experience serious handling problems - and many did. Keep the proper tire pressure and a Corvair out-handled just about every American car of the day and most foreign ones too.