Have a old '67 F250 HighBoy that has a 390 out of a 1968 vehicle. Far as I know it's stock, and runs on a 2 barrell carburetor so it's not making gobs of power. I've been running 15W-40 Rotella in it, but as I understand it, the zinc levels have dropped substantially in the new formula so should I run something else? Getting ready to change the oil and wanting to know if the Rotella is still safe to run or if I should go with something else. This is a flat tappet cam engine so it needs oil with lots of zinc in it I've been told and HDEO's used to be the ticket but not sure if they are anymore.
Thanks all!
Thanks all!