so im at 115k , I use mobil1 high mileage in my suburban, but im worried about using in this thing due to the seal conditioning ingredients. would anybody recommend using a high ZDDP oil like brad penn or some other racing oils? again , im just worried about what additives might do what to this motor at this mileage. for my first change I ordered up some amsoil and a ford racing filter. I don't plan on thrashing the car , but as everybody does , will have the occasional fun with it

 

I use the Mobil ! high millage in my explorer and have had no issues with it. Amsoil is great also although more expensive.

 

I always wondered if there was actually anything different about the "high mileage" oils; other than the label?

anyway, I'm thinking a good full synthetic like Mobil 1 EP is probably fine regardless of mileage; and I doubt any high mileage additives would do any harm (but not sure about that)

 

I did a quick read , and basically the HM oils have boosted levels of seal conditioners which I heard make the seals and gaskets swell a bit to prevent leaks. I don't know the chemistry behind it , but I didn't want to cause any leaks by affecting any internal seals. the 4.6 might be different from the small block chevy in the suburban. as far as higher zinc ZDDP oil , that's what I wonder will be better for these higher mileage.