Another question for all of you (a slightly different question than has been dealt with in this string): I have a '91 Porsche 911 that spends most of its life in storage. Have used Mobil 1 since new, and would like thoughts about oil/filter change TIME (rather than mileage) frequency. Have only put on 190 miles since last change 14 months ago. Should I really be changing oil every X months regardless of mileage?

Another question for all of you (a slightly different question than has been dealt with in this string): I have a '91 Porsche 911 that spends most of its life in storage. Have used Mobil 1 since new, and would like thoughts about oil/filter change TIME (rather than mileage) frequency. Have only put on 190 miles since last change 14 months ago. Should I really be changing oil every X months regardless of mileage?
Don't worry about the time spent in storage, within reason.

Oil 'wears out' when the engine is running. The moving engine parts tend to chop-up the oil's long molecules, thus thinning the oil. Heat causes the additives to dissipate, and blow-by gases and dirt contaminate the oil.

So, storage, even for years, will not wear oil out. The key here is the oil must be fresh before going into storage, as the contaminants from old oil tend to corrode metal parts over time.

If that 190 miles has been accumulated by just a few long trips, where the oil has had a chance to fully warm up, then it's still good for quite a long time to come.

But if it's been accumulated by many, many cold starts and very short drives, then a change will be due soon, due to oil contamination.

Don't worry about the time spent in storage, within reason.

Oil 'wears out' when the engine is running. The moving engine parts tend to chop-up the oil's long molecules, thus thinning the oil. Heat causes the additives to dissipate, and blow-by gases and dirt contaminate the oil.

So, storage, even for years, will not wear oil out. The key here is the oil must be fresh before going into storage, as the contaminants from old oil tend to corrode metal parts over time.

If that 190 miles has been accumulated by just a few long trips, where the oil has had a chance to fully warm up, then it's still good for quite a long time to come.

But if it's been accumulated by many, many cold starts and very short drives, then a change will be due soon, due to oil contamination.
Thanks very much. Very helpful!

Thanks. Didn't think of testing/analysis.