Rear differential fluid?

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jdyates

Ghetto Racetruck
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Recently I've replaced all my fluids (yes, even headlight fluid :lol:) except the rear diff. What fluid and thickness do you guys recommend?

The dude at O'Reillys said i should go with the thickest they have, which is 85w. Not sure if it makes a difference, but for reference, i pretty much only do city driving (stop and go), and temperature here can get down to 50*F during winter and EASILY hit 100*F during summer....so varied temps.
 

DRAGGIN95

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I have alway's used 80-90w gear oil, and I have put hundreds of thousands of miles on rear end's with that weight oil with no problem's, but you need to be sure to check to see whether your rear end need's the hypoid gear additive, a lot of locking rear end's need this.
 

DRAGGIN95

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Find out what rear end ratio you have and also look to see if you have a locker, it will be in your glove box in the G codes GQ1 -- AXLE REAR, STD RATIO
GT4 -- AXLE REAR, 3.73 RATIO
GT5 -- AXLE REAR, 4.10 RATIO
GU4 -- AXLE REAR, 3.08 RATIO
GU5 -- AXLE REAR, 3.23 RATIO
GU6 -- AXLE REAR, 3.42 RATIO
G80 -- AXLE REAR, LIMITED SLIP (POSITRACTION)

HC4 -- AXLE REAR, 4.56 RATIO

Then I would check either your owners manual if you have it, or check with a chevy dealer to find out if your rear end need's the hypoid fluid.
 

Hezsus

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i thought that the factory lockers werent supposed to get any additive? I just run 80-90 in mine as well.. but mine did wear out and now it just works as an open diff.
 
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