Show us your manual and tell us what oil you use

[AuthorEditor]

I didn't realize they even had 5W-20 in 1966.

 

[hominid7]

I've owned my 2001 Mazda 626 since new. The car has seen lots of Motorcraft 5w30 as well as Quakerstate, Pennzoil, and Castrol, all in 10w30. The car now has 171,000 miles on it and so far no oil related issues. Oil changes approx every 3000-5000 miles.