This is Why I Don't Change My Oil

[patrickt]

My last oil change was four years ago. I like to get yearly UOAs by Blackstone Labs and the one below came today. I look, of course, for wear particles, but I also look for anything that's in the oil that shouldn't be in the oil, like water, antifreeze and gas. That, along with the flash point, viscosity and TBN tell you whether or not you have a problem and whether you need to change your oil or not. The "I change my oil yearly for peace of mind" mindset is for idiots. Not to mention that SAE has papers supporting the theory that changing your oil too often actually increases engine wear. Zinc/Phos numbers can be misleading though because you don't know if that is "used" or not. But unless you have a solid flat tappet you don't really care about that as much as I do.