Oh, I thought you were talking about classic muscle cars. Ever since SL rated motor oils here, an additive known as ZDDP has been reduced and will soon be eliminated. ZDDP (Zinc Dialkyl Dithio Phosphate) is an important antiwear additive in motors using flat tappet valvetrains With the reduction and soon the elimination of ZDDP, a lot of those motors will start eating camshafts. The lobes will wear down. Best bet for somebody who wants to keep such a car is to stock up on older oils. Or just rebuild the motor Just like when lead was removed from gasoline, ZDDP will also have a negative impact on older vehicles and also on older commercial equipment (Valve in head motors, old tractors, etc). So not only did the older motors have to be rebuilt with hardened valve seats to prevent wear, they will need roller lifter camshafts to prevent flat tappet lobe wear Just about every modern "crate" motor already has roller lifters. There are minor performance improvements due to the reduction in friction. No modern motor needs or requires ZDDP. The general consensus is that ZDDP could destroy the catalytic converter over the extended emissions laws in California and those states with California emissions
