Oil with the proper amount of
Zinc Phosphate in it is still available. Joe Gibbs racing has it in both break in conventional (BR) and syn. versions. Also I believe Valvoline VR-1 racing has the
Zinc also. There is one other producers that excapes me right now. Also Chevy's (bad word on this sit) break in
oil is largely ZDDP. The racers know where to find it as a lot of them still run flat tappet.