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Re: Oil Change Opinion

First off, this thread has absolutely nothing to do with my WRX. I change the oil faithfully every 3000-5000 miles.

However, after doing an oil change on the WRX this past weekend I checked my records on my wife's Legacy and realized that it has been nearly a year since I changed out the oil . . . but here's the deal . . . she's put on slightly more than 2000 miles . . . that's it since she was out of work for quite some time and then landed a local job with maybe a 10 minute commute.

Now I know the manuals all say X miles or Y months . . . just how bad is it to go over the time limit? I realize miles = wear and tear on the engine and hence the reason for the oil change, but if the car isn't actually under power and is simply not run a lot is it crucially important to meet the time limit?
 

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I'm not an expert on oil but I would think part of the answer would depend on the type of oil used. Synthetic would probably be a lot better and able to handle the extended time.
 

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The oil will lose over time the ability to resist pH changes and thus corrosion. A measure of the ability is the metric, TBN, or total base number.

Change it and live life.
 

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Over time acids in the oil increase and additives break down. The short trips never let the oil get hot enough to burn off condensation and impurities in the oil which makes those two things worse. I would change it at least every year regardless of mileage. cheap insurance.
 

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I have a 1964 farm tractor. It sets for over a year at a time sometimes. I have changed the oil in it twice in 14 years. It still runs fine whenever i start it. Oil as we know it in the refined form for automotive use is a relatively stable substance. It does degrade when combustion products are introduced but so relatively slowly. Hidden from light in the oil pan, it should act as the stuff in my tractor does :)

I'd say "not crucial at all."
 

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I dont think you have much to worry about. Ive changed my oil yearly in my S2000 for the last 4 years and even had the oil analyzed. Granted I only drive the car about 1000-1200 a year, its always still in very good condition.
 
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