When to Change Engine Oil
Proper maintenance of your engine's lubrication system will help ensure a long life of the engine. Let's get something straight. The reason for having to change the oil is contamination. Oil doesn't 'wear out'. If it weren't for contamination, you would never have to change it. Oil contamination comes in the form of blow-by gasses. This is the small amount of air/fuel mixture that escapes the cylinders through the rings, on the compression stroke. Yes, all engines do it. Blow-by is a normal part of engine operation. That is why there is a PCV system, which should also be serviced with an oil change. It consists of a crank case air filter, and a PCV valve.
When you check your oil and it is a quart low, it is usually from the fuel that has contaminated it and broke it down, through the normal blow-by. This is when you should change the oil.
A warning about those high price synthetic oils:They don't get contaminated. Do you think that's a good thing? I hope not, because this will let the blow-by gasses (raw fuel) sit on top of the oil in the pan. Now when the engine is running, there is no oil in the pan it is up in the engine, doing its job. This leaves a straight shot of raw, uncontaminated gas in the bottom of the oil pan, for the pump to suck it up. Once the oil pump sucks up gasoline, it is damaged. In my 11 years as a shop owner, I have never changed an oil pump on an engine that didn't use synthetic oil. That right there should tell you how important it is to use the proper engine oil that is recommended by the manufacturer of your vehicle.
When choosing the type of oil for your engine, the name on the bottle makes no difference at all. It is the API rating that you should pay attention to. If the oil doesn't match the API rating that is recommended for the engine, then it is the wrong oil. Fancy stickers and expensive brand manes will not keep your engine running longer, though some of them do offer extra warranties. Choose your oil wisely, and take the advice from the people who make your car as well as the advice from me as the one who works on your car.
Remember, synthetic oils are bad okay.
