Ask the Car Guy: The Oil Change Myth

Q:

Is it ok to go past my mileage on an oil change?

A:

Ah, that age old ticking time bomb known as “the miles past your oil change”. You look at the sticker on the inside of your windshield and literally count the miles you have put on BEYOND the recommended change interval, wondering when implosion, explosion or some type of major detonation will occur.

The good news is that for the most part, going beyond within reason, isn’t the “death knell” for your engine.

Motor oil by design, lubricates moving parts in most all internal combustion engines and helps minimize the friction between these internal parts (which causes wear). Motor oil creates a slippery "film" that prevents direct contact with these parts and helps prevent abnormal friction, higher heat and increased wear, as the engine is operated.

Now, the rubbing of the parts together, even aided by the film the oil provides, still produces wear and even microscopic metal fragments that are picked up by the oil filter and oil pan. Plus, the heat and hard work of the internal parts causes the oil to become dirty and “thicker” since the additives break down over hard usage and time, thus reducing the oil's effectiveness at keeping things “slippery.”

Here is where it gets good: Fragments in the oil pan, potential sludge, heighten operating temperatures in the engine, lower RPMs, increased fuel consumption and of course, cause potential engine failure.

These are all BAD things that can come from ignoring that sticker and postponing your oil change.

The type of miles you have driven since your last oil change - distance driven, type of trips taken, number of cold starts, etc. - still remains the BEST indicator of when oil should be changed.

Luckily, today’s advanced vehicles have the technology to take all these things into account and then some, in order to trigger the “idiot light” on your dash and remind you that it's “time." But for some of us, the oil change sticker from the dealer, “quick lube” or reputable local shop are still reliable reminders.

Try not to go thousands of miles past the interval and most “experts” say that you will be ok. But I don’t recommend bending the rule, because in the end… a complete engine repair or replacement expense is far more more costly than a simple oil change.  

Don’t you agree?

Editor's Note: Blain Boudreau is a 20 year veteran of the auto industry with a vast array of "car guy" knowledge. Have an auto question for Blain? Email Andy.Ambrosius@patch.com.