Time to perform the first oil change on the 428CJ Cougar and I am looking for recommendations on the best oil to use. I have heard some using zinc additives to their oil while others are using oil with zinc already in there what are your thoughts?
while not on that list, Castrol GTX Classic looks to be a good candidate for older flat tappet engines.
Don’t be tempted to continuously run break-in oil. While they are very high in zinc, they lack some of the other components for a well rounded engine oil.