Newer tech motors with roller cams which make up the majority of the new car market do well with
synthetic oil. I use it in all my new cars.
But, older tech motors with solid lifter flat tappet cams need the lubrication of a petroleum based racing
oil that has the
zinc still in it and which might be gone soon. If you open up a quart and can't smell the
zinc, it doesn't have it. The smell is more like a stink. The only ones that currently still have it are the Pennzoil
25w50 and the 76 Nascar 20w50. I have a good stock of both preparing for the EPA extinction which is soon to come.