So I have no idea what is in the truck as it is recently new to me. I want to swap out the fluids so I have a starting point. What lube do these axles require? I recall GMs having to put in some special lube additive? is that required?
CK5
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front and rear diff lube
- Thread starter Justin Fleming
- Start date
If it has a limited slip it needs the correct lube and the additive for the clutches...open diffs can use regular 80W-90 gear oil...look on the bottle,most gear oils say on the label if they are rated for limited slip diffs,I would still add the anti-chatter lube too...
How do I tell if it is limited slip? I assume it is only in the rear?
Once the diff cover is off you'll be able to tell right away...you can google "GM limited slip differential" under "Images" and it'll show the different types available...a Gov-Loc has no clutches ,so it doesn't really need the posi compatible gear lube or additive,but it wont hurt to use both in any diff,open or not,other than cost you a few extra bucks..
One fast way that can be used to tell if it has a limited slip (other than a tag on the filler plug stating so),is to jack both rear wheels off the ground,spin one tire by hand,and watch the other tire--if they both revolve in the same direction,its a limited slip,if not,its probably an open diff--I say "probably" because a gov-loc wont "lock" until one tire spins faster than the other...so it might appear to be "open",but really isn't..
One fast way that can be used to tell if it has a limited slip (other than a tag on the filler plug stating so),is to jack both rear wheels off the ground,spin one tire by hand,and watch the other tire--if they both revolve in the same direction,its a limited slip,if not,its probably an open diff--I say "probably" because a gov-loc wont "lock" until one tire spins faster than the other...so it might appear to be "open",but really isn't..
Going on a limb here, no GM trucks used true limited slip, at least as far as I know of for '73-up. Limited slip was all cars (even though same RPO), but G80 in truck is always the Eaton Gov-lock.
