Quote Originally Posted by IC2 View Post
Roger - not sure that NAPA numbering thing is 100% across the board, but every WIX/NAPA filter I've had has cross referenced that way.

My fall out with Castrol has been with vehicles that never used a drop of oil between changes suddenly starting to need 1, 2 or more in the same period of mileage. Then changing over, no longer used any again. That had happened on several vehicles. Is it bad oil? Of course not. But I've just had less then good experiences and more then once
I've had the same experience with castrol in any of my "hopped up" gas engines. I quit using it for the same reason years ago. I know a lot of dirt track guys that quit using it too, for the same reason. Most of those guys went to John Deere oil because they could buy it 5 gal at a time and it still had the zinc additive in it.