arbeitm

Whenever I see discussions on the oil change intervals, it is always discussed in miles. I know that it is best to change the oil every 3,000 miles (instead of the recommeded 15,000 miles for an n/a). But what is the best interval in months?

I don't get to drive my car all that much, so if I wait 3,000 miles it will probably be in about 6 months. However, I can't see changing the oil which may have about 1,500 miles on it every 3 months. That seems excessive. I was thinking of something like:

3,000 miles or 6 months whichever comes first.

What are your opinions?

who1

My '89 NA sees about 3k a year. I just change once a year in they fall.

Tony K

My understanding is that if you use synthetic oil, you can leave it in there for years, because unlike petroleum oils, synthetics don't form acids and break down from the heat and the combustion process. The only thing you would really have to worry about is possible mixing with water from condensation inside the crankcase (but I don't think that is really an issue with 944s).

As for petroleum oil, well . . . I don't know . . . it has been a long time since I used it, and I always did the 3 month rule. I don't think 6 months would hurt, but I don't know.

Cheers,

arbeitm

I'm using Mobil 1 if that helps clarify a bit.

Tony K

Then change it every 3000 miles. It will be fine.

jim944s2

I put very few miles on my S2, but there are auto-x miles in there, -and I use Mobil 1. My feeling is that it costs about $50 for a change with filter, and if there's ANY benefit to changing the oil every 6 months or so that is a very small price to pay.

Sasquatch

I too have a garage queen 944na. I now change my oil every 2 years (mobil 1). When I daily drove it, yearly oil changes (about 12k miles) was the norm.

We as a society change our oil waaaaaaaay too often on modern cars. There are signs that we are changing our ways though.

jim944s2

Here's another way to look at it from a 'value' standpoint: when you sell your car, would it be worth anything to the prospective buyer that it had Mobil1 every 6 months, or every 2+ years? Or if you were buying?

hosrom_951

I replace mine with Mobil 1 every 10,000kms or 12 months (though this never happened), and right now i am ovr due by 600kms or so (waiting for more parts to arrive for an oil pan gasket job) and LOTS of holidays here, adding more time

arbeitm

I think I'm going to stick with my original plan:

3,000 miles or 6 months, whichever comes first

Matt H

Matt, oil change intervals are 3 months/3K miles because average mileage is still figured at 1K miles per month (though that figure will be moving to towards 15K per year very soon).

I agree, however, that we change our oil FAR too often. There is an "oil bible" on the internet that shows all sorts of research. If using synthetic I think that 10K might be my interval. Actually, it IS my interval with Royal Purple 5W-30 in my BMW.
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Sam Lin

With synthetic, I go by mileage, 5000 miles. I'd change at 5 years, but my cars haven't sat that long before.

Sam

Sasquatch

I think that all you guys who change their Mobil 1 at 3k miles ought to start selling your used oil to us guys who know that 3k aint nothing for Mobil 1....... Just joking, but it could happen... I have a couple of cars that I would willingly put used Mobil 1 in if I knew the source and the handling....

seb928s

Right now I do work at an oil change place. Man that Mobil 1 comes out clean after 5k on it. That's what we right the sticker for. I feel with the amount of oil we have in our engines you can do that oil changes 7-10k with synthetic oil. I would change the oil filter after 3-4k. I seen some nasty oils coming out only after 3k but those are petroleum oils and in cars that haven't been turned up in years. In the average car even the petroleum oils that have low surfer it looks pretty good after 3k. Anyhow I still stick to 3-4k oil changes using my mobil 1 oil. I think I'll start putting that into my daily driver VW GTI from now on...

Dan87951

I check my engine oil regularly, if it looks dirty after your 6 month period change it otherwise leave it in there I'm sure its fine. Just use common sense about it. My car does not see 3k miles a year either now that I have another car to do my daily driving in and I change my oil annually now.