BRAD PENN RACING OIL .. is joe gibbs oil .. and thats what i run in all my old cars ..AMALIE RACING OIL is also a good zinc oil ..i dont know about others cause i dont trust them .. castrol has never produced one drop of oil they are just a great marketing company .. most of thier products are exxon/mobil and blended to spec ..beware zinc levels are not up to spec in any new gf-5 oils and will kill your cam quick ..