Originally Posted By: Gene K
Originally Posted By: dlundblad
Originally Posted By: cog
My 89 Cherokee has 508,000 miles with mostly Castrol 20w-50 used.
The last few years have been the Super Tech 20w-50 at 3000 to 5000 change intervals.
Do you guys think im harming the old mill and does the ST have the Zinc that my motor needs?
In all fairness, I am taking the second sentence to mean the Jeep has only been on 20w50 the last few years.. so no, 20w50 didn't get the Jeep this far.
The American side of me says that is too thick, but I am sure Australians do it all the time in hot climates.
I would personally run a 10/15w40 though. Zinc isn't necessary, but the 4.0 does seem to love it. A diesel oil will be loaded with it.
I'm taking the first and second sentence combined to mean 300,000+ miles on Castrol GTX 20W50 and ST 20W50.
Yeah I must have missed that. You are right.