GM 75W90 DIFF LUBE
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JTK
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No clue on who makes the GM stuff, but the OEM synthetic 75w-90 I drained from my 2005 trailblazer came out black at ~20Kmi. I refilled with M1 75w-90. IMO- I wouldn't run 85w-140 unless the truck sees extreme ambient temps or does a boat load of towing. Other than that you'll just waste gasoline.
Joel
Joel
i agree, 140 to thick for every day driving.
I was not aware they have a new gear lube. They started to use synthetic with the new 99+ models.
At one time it was made by Texaco but that was back in the late 90's. How do I know it was Txaco/ It was mentioned in a Service Bulletin I read. No telling who supplier now but GM seems to be using Petro Canada for fluids recently, AT II, Dexron VI etc.
I agree, 75W-90 is the correct fluid, 75W-140 would not suitable for use in a GM SUV and could be a problem under warranty.
At one time it was made by Texaco but that was back in the late 90's. How do I know it was Txaco/ It was mentioned in a Service Bulletin I read. No telling who supplier now but GM seems to be using Petro Canada for fluids recently, AT II, Dexron VI etc.
I agree, 75W-90 is the correct fluid, 75W-140 would not suitable for use in a GM SUV and could be a problem under warranty.
How often do you guys change the diffs? The book says 50k with the trans which is DexronVI. I'm at 6000 mile and was thinking of changing the whole drive train after the break in. I did change the transfer case from DexronIII to Mobil1 Synthetic ATF and am running Mobil1 or PP in the engine.
"" 140 to thick for every day driving.""
gear set design is more the "severe" part Not so much how you drive tho high temps will cause more gear wear partly due to oil thining in hypoid gear sets heavier oils will reduce wear over "thinner" oils, a 75/140 is better (as far as gear wear) than a 75/90 oil.
bruce
bruce
gear set design is more the "severe" part Not so much how you drive tho high temps will cause more gear wear partly due to oil thining in hypoid gear sets heavier oils will reduce wear over "thinner" oils, a 75/140 is better (as far as gear wear) than a 75/90 oil.
bruce
bruce
just a comparision
a HOT 200F 75/90 gear oil is about same vis as a 200F 10/30.
a HOT 200F 75/140 gear oil is about same vis as a 200F 20/50.
bruce
a HOT 200F 75/90 gear oil is about same vis as a 200F 10/30.
a HOT 200F 75/140 gear oil is about same vis as a 200F 20/50.
bruce
check that I'm to low by 1 grade but you get the picture I guess
bruce
bruce
I have Mobil 1 75w-90 in the front axle of my 2500HD and Royal Purple 75w-90 in the rear. I planned on using the same oil in both,but none of the parts stores near me had enough of either to do both. I wasn't going to pay $25 a qt for GMs oil either.
I have a 2002 Yukon XL 4WD, 54k miles, and changed my front & rear differential fluid last month. Drained the factory fill, put in Redline 75w90 and noticed a positive difference immediately. I'm not sure if it was real or not.
The old gear oil was translucent black in both, darker in the front. The front magnetic bolt had a good bit of breakin metal on it, rear had no material of significance. I wish I had changed it much earlier, but thought I was doing pretty good by changing it at half the recommended interval. If I had it to do over again, I would probably change it at 10k.
I also changed the transfer case fluid with GM Autotrack fluid. Old stuff was a little discolored, but not much.
The old gear oil was translucent black in both, darker in the front. The front magnetic bolt had a good bit of breakin metal on it, rear had no material of significance. I wish I had changed it much earlier, but thought I was doing pretty good by changing it at half the recommended interval. If I had it to do over again, I would probably change it at 10k.
I also changed the transfer case fluid with GM Autotrack fluid. Old stuff was a little discolored, but not much.
tjones
2002 is about the time they swithced to the new AT II transfer case fluid. Not recalling exactly when the change was made, its possible the fluid that was oem was not the A/T II fluid but the first iteration that dated back to the 90's so that could account for the color difference. I think the old was a very dark red.
2002 is about the time they swithced to the new AT II transfer case fluid. Not recalling exactly when the change was made, its possible the fluid that was oem was not the A/T II fluid but the first iteration that dated back to the 90's so that could account for the color difference. I think the old was a very dark red.
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