street driven drag car I use brad penn grade 1 race oil synthetic blend and K&N filter... used to use Fram HP4 (high pressure, high performance) filter without any issues but I like the nut on the bottom of the K&N and the filter media is finer. That said, with my milder BBC I ran Castrol GTX for years without any trouble... as with anything, I guess it depends what you want to do with it.