Stupid Question: Lower unit gear lube same as 80W-90?
I have several bottles of lower unit gear lube left over from an older Merc engine that I no longer own. I'm wondering just what the differences between this stuff and regular 80W-90 gear oil is. The lables state that it "For use in all outboard and sterndrive gear units specifying SAE 90, 80W90 or 85W-90, including OEM Type "C"."
I do have an older Chevy truck that uses 80W-90 in both the rear and front differentials (no posi) and I would like to use the lower unit lube in these if it is compatible. I imagine that the marine variant has more corrosion inhibitors than straight 80W-90, but other than that, are there other differences?