I was running 5 or 10W-30, don't recall, whatever is states in the manual to use. I went to the 10W-40 because while out wheeling, after being out for a few hours the oil pressure would seem to dip so I figured the heat was thinning things out, so I stepped up a grade. WA state, so 30's to 40's.

84 Ext. Cab Pickup.