2005Redfire6

Really? You must not drive the car, I have read though that you should still change it in time intervals and especially if it is sitting like that.

Nuke

I don't have anything hard and fast about changing oil based on time but since I've been driving my Stang a LOT less than I used to, I've gone to time-based oil changes and I've done it on occasions with other vehicles. My rule of thumb has been 6 months on dino and blends and 1 year on full synthetic. Now that I'm barely putting 3k-5k miles on the Stang in 1 year, I've switched from Amsoil to Pennzoil; still getting great protection but at about 66% the price.

I have a feeling that full synthetic is good beyond 1 year but until I get my hands on something substantiating that, I'll err on the conservative side.

11gt

I change the oil in my mustang every 5000 miles with Mobil One 5W20 and a Motorcraft filter. In this duration, the engine uses about 1/2 of a quart of oil.

PNYXPRESS

I never understood the whole "change the oil at least once per year" gimmick. If oil doesnt go bad on the shelf why will it go bad in my engine? And it cant be about moisture because oil and water DONT mix. I think that was something the oil companies thought of just so people would purchase oil even if they didnt drive their car and need to replace it on mileage.

11gt

Water in oil emulsions are quite possible with the right surfactant.

Nuke

From my oil analysis training many moons ago, the concern wasn't that "the oil goes bad", it was about the protective packages ADDED to the oil eventually get "used up" such that the oil can no longer combat moisture, acids, etc. Think of any of those packages like how a desiccant works; desiccant can only absorb a given amount of moisture at which point it fails to do what it was intended to. The only way to know if those protective properties of the oil have sufficient life is to perform an oil analysis. I feel fairly confident that my oil is still good for additional mileage for both the amount of time AND mileage I put on them but the cost of the analysis (plus pulling the sample) IMO are just as easily and economical as simply doing an oil change.

Although the geek in me really wants to have the analysis done...

157dB

Be sure and pre-fill the filter to prevent the dreaded 'after changing the oil dry start-up' problem. Praying for the oil light to go out after starting the engine
only does so much good if the oil pump has to fill up an empty filter before
feeding oil to the engine that has drained back when the filter was removed.