I have been doing research and watching videos from The Motor Oil Geek, and I think I am going to start using Mobile 1 European 5w-40 in my 83. The ZDDP package is very similar to pre-1994 10w-30. Today's 10w-30 is capped at 800ppm. 50 weight oil has more ZDDP, but if you go too thick you lose a...