Differential Fluid Change Question

jollyjerry · Sep 29, 2016

RichLo said:
I usually do a 50/50 mix of lucas oil stabilizer whenever dealing with older differentials

What's the reasoning behind having stabilizer for older diffs? Just curious

RichLo · Sep 29, 2016

lucas is good stuff and can prolong the life of older diffs, transfer cases and manual transmissions. I've had a couple noisy differentials that lucas really quieted down. That's one of the few products that actually does what it says it does and that I use regularly.

Ironhead · Oct 3, 2016

I got 75-90 from the local Chevy dealer. It's synthetic. Truck has a 10 bolt Gov Lock. So far, so good.

HGKx · Feb 24, 2024

Jrgunn5150 said:
This is correct, some people erroneously call the G80 a posi or limited slip. It is in fact a locker and requires nothing more than gear lube.

Just so I make sure I have my ducks in a row... on a RPO reader for my VIN, it says:

"G80: Axle, Rear. Positraction, Limited Slip Positraction L/SLIP R/AXL"

Do my eyes deceive me? Or are you say no additive for the front diff exclusively? No additive for the rear either I take it?

454cid · Feb 24, 2024

HGKx said:
Just so I make sure I have my ducks in a row... on a RPO reader for my VIN, it says:

"G80: Axle, Rear. Positraction, Limited Slip Positraction L/SLIP R/AXL"

Do my eyes deceive me? Or are you say no additive for the front diff exclusively? No additive for the rear either I take it?

Whatever you used to generate that list, is using a car definition for the G80. RPO's can change in the particulars from year to year (especially if there is a platform change) and model to model. A G80 in a car would be some sort of limited slip or "posi". In a GMT-400 truck it's the gov-lock, which is a particular locker design. There's no slip. It's either locked, or it's not. A limited slip additive can mess with them because the locking mechanism that locks/unlocks the differential does use clutches. So the lock up is either delayed of completely nonexistent.

There is no locker in the front. You could probably run an additive up there, but there's no reason to, unless you're just trying to use up a gear oil with it already mixed in.

HGKx · Feb 24, 2024

454cid said:
Whatever you used to generate that list, is using a car definition for the G80. RPO's can change in the particulars from year to year (especially if there is a platform change) and model to model. A G80 in a car would be some sort of limited slip or "posi". In a GMT-400 truck it's the gov-lock, which is a particular locker design. There's no slip. It's either locked, or it's not. A limited slip additive can mess with them because the locking mechanism that locks/unlocks the differential does use clutches. So the lock up is either delayed of completely nonexistent.

There is no locker in the front. You could probably run an additive up there, but there's no reason to, unless you're just trying to use up a gear oil with it already mixed in.

Thank you, sir. Super new to the truck world, so I appreciate the detail! No additive, got it.

Schurkey · Feb 25, 2024

The recommended rear axle gear lube for G80 is the Grape-Juice stuff. ACDelco 10-4060

www.amazon.com/dp/B000QGOX1A/?coliid=I2EQWKHVBIDUK1&colid=2VLYZKC3HBBDO&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

Differential Fluid Change Question

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