Gotcha on the fuel thing. Makes sense.

 

It's not the oil, but the additives that break down. You also did not account for the oil filter.

I'm not saying that you're wrong, but i'm not saying that you're right either.

 

Well some of those additives are there to make the oil last longer . But hey, there is an easy answer to this - go get your oil analyzed at your next oil change.

 

pretty good list for most non enthusiast drivers. those of us who are enthusiasts kind of take things to the extreme; we know we're blowing money but we dont' care!
i agree with the oil analysis. send it in; it's cheap and you can actually save money if your oil is working well up to 10k miles or so instead of just dumping it out before it's really necessary. a lot diesel guys i know are running ove r 10k mile intervals after they've been analyzed. of course they're using amsoil, or other high end oils too. regular dino oil won't get you to those high mile intervals for the most part.

 

I sometimes do it myself. On the 2.5s, it's a cinch. Both the oil filter and drain plug are right there, up front, just under the front bumper...and the high ground clearance of some Subies means you don't have to fool around with a set of ramps either.