15/40 only because I inherited about 4 cases from an inlaw that passed away, runs with no problems.

 

its about time for a change, so ill rethink the situation after that.

 

Oil pressure shouldn't vary by more than 5 psi -10 if extremely cold. The truck I bought was nursed with 20W-50W oil to compensate for a failing pump before I bought it - now I'm paying he consequences.... Even with the heavy weight oil - the pressurs would sit about 10 at idle and only go to about 35 at cruise. I picked up the truck in Ohioand had a lot of lifter clatter going into the mountains of Kentucky (going downhill) - did an oil change with a quart of Lucas oil and 20-50 and managed to make it home to FL with about 45 PSI at cruise.

Bottom line - change the pump now before you suffer engine damage.

 

Mine is at about 50 cold, 35 warm. I think it's about the same while driving, I never really looked at it before while driving. Don't know what oil was in it previously since I got the truck recently. I switched to Royal Purple 5W-30 today for the colder weather of alaska. So I'm guessing that's why my pressure is a little bit low.

 

45 PSI at idle, 50 PSI while driving. Oil change 3 days ago.

 

About 38/39 at idle and 40+ running. I'm using a full synthetic blend (can't remember what brand).