Another option is to find a vintage Cadillac collector and ask them what they use. I'm sure they could tell you which modern oils are compatible.
GM #1052271 substitute - Ancient posi trac juice
- Thread starter GS380T
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Asking vintage fools for advice is like asking a drive thru fries handling clown for opinion on brain surgery
Back when I had a 2003 Chevy Blazer with the G80 locking differential, GM had specced to use only their fluid. I learned I could just use a GL-5 75w90 or 80w90. Things have changed a lot since your manual was written, so you could either use 80w90 or 75w90 with LSA in it. Can you verify it is a Eaton G80 differential? If so, then I know limited slip additive is not needed.
Back prior to the later 1980s, when GM termed their limited-slip rear axles "PosiTraction", rather than G80 "Locking Differential", the normal rear axle grease was used with the friction modifier additive 1052271. One bottle was the typical dose.
There are TWO types of (generic) P-Tracs, the older style is "locked until it unlocks" (spring-loaded friction plates) and the more recent ones are governor-weight controlled "unlocked until it locks". When GM went to the latter type in the later 1990s, they did not recommend the use of the prior additive, unless there was some operational issue where it might help (TSBs noted these things).
It was very common for, on left hand turns, for the locked-up plates to seem to "catch" before they fully unlocked (slipped against spring pressure), which is where the friction modified "additive" came into play. Sometimes, there was a slight pop when the plates started to slip in that corner (left hand was usually the worst, for some reason).
To help get the additived-fluid between the clutch plates, some bulletins mentioned making about 15 revolutions (tight turns) in each direction. I don't know that that was a good fix, as the straight-line driving after that might squeeze that lube from between the plates.
We bought a new 1969 CST-10 pickup with a 3.73 PosiTrac in it. It had that "lh turn catch" in it from new. Even with the additive. These were the P-Tracs which had four springs keeping the clutch pack engaged when the vehicle was running straight. Later '70s versions used an S-shaped spring to replace the earlier 4 spring versions. My '77 Camaro with P-Trac was this way and did not exhibit the same "catches" on lh turns that our '69 pickup did, for some reason.
There were usually a red plastic "tag" attached to the rear axle drain plug, noting the "PosiTraction" rear axle was present and "special grease" was required for it, when new.
There was NO difference in the rear axle gears themselves, just the innards of the differential case, in PosiTraction rear axles. The "open" axles just had the normal spider gears and such, whereas the P-Tracs had the clutch plates and springs.
In the mid-1960s or so, GM did have a particular part number rear axle fluid, specific to the P-Trac rear axles. Normal stuff with the additive already in it, I suspect. But as nobody stocked it, the bottle of additive became the way things were done.
Just some historical information and my experiences,
CBODY67
There are TWO types of (generic) P-Tracs, the older style is "locked until it unlocks" (spring-loaded friction plates) and the more recent ones are governor-weight controlled "unlocked until it locks". When GM went to the latter type in the later 1990s, they did not recommend the use of the prior additive, unless there was some operational issue where it might help (TSBs noted these things).
It was very common for, on left hand turns, for the locked-up plates to seem to "catch" before they fully unlocked (slipped against spring pressure), which is where the friction modified "additive" came into play. Sometimes, there was a slight pop when the plates started to slip in that corner (left hand was usually the worst, for some reason).
To help get the additived-fluid between the clutch plates, some bulletins mentioned making about 15 revolutions (tight turns) in each direction. I don't know that that was a good fix, as the straight-line driving after that might squeeze that lube from between the plates.
We bought a new 1969 CST-10 pickup with a 3.73 PosiTrac in it. It had that "lh turn catch" in it from new. Even with the additive. These were the P-Tracs which had four springs keeping the clutch pack engaged when the vehicle was running straight. Later '70s versions used an S-shaped spring to replace the earlier 4 spring versions. My '77 Camaro with P-Trac was this way and did not exhibit the same "catches" on lh turns that our '69 pickup did, for some reason.
There were usually a red plastic "tag" attached to the rear axle drain plug, noting the "PosiTraction" rear axle was present and "special grease" was required for it, when new.
There was NO difference in the rear axle gears themselves, just the innards of the differential case, in PosiTraction rear axles. The "open" axles just had the normal spider gears and such, whereas the P-Tracs had the clutch plates and springs.
In the mid-1960s or so, GM did have a particular part number rear axle fluid, specific to the P-Trac rear axles. Normal stuff with the additive already in it, I suspect. But as nobody stocked it, the bottle of additive became the way things were done.
Just some historical information and my experiences,
CBODY67
