Getting ready for the drag racing season and need to purchase oil. Been running Schaeffers Supreme 7000 20W/50 and their Semi-syn rear end lube. Ran AMSOIL in the tranny. Both engines are 500+ cubic inches, one is a glide and the other a turbo 400. Any opinions on Schaeffer for oil, tranny and rear end? Like to keep the same for all but want to make sure I am buying the best product(s) for my investment.