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Discussion Starter · #1 ·
Hi There just a quick question, I Have a 94 FB TA, LT1 and I'm going to drain the rear axle as I dont think theirs any additive in it and I was just wondering what the right amount of additive is and can I fill the rest of the way with a full synthetic gear oil or do I need a dino based gear oil. Thank

Tony
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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The GM limited slip differential (LSD) additive comes in a small (4 oz) container. The rear holds a little less than 2 quarts of GL-5 75W-90 lube. Add a quart of lube, add the full container of additive, add the rest of the lube until the level in the rear is even with the bottom edge of the fill hole.
 

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Discussion Starter · #3 ·
The GM limited slip differential (LSD) additive comes in a small (4 oz) container. The rear holds a little less than 2 quarts of GL-5 75W-90 lube. Add a quart of lube, add the full container of additive, add the rest of the lube until the level in the rear is even with the bottom edge of the fill hole.
Cool, thanks Fred. can I use a synthetic lube or does it need to be dino?
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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I really don't think it matters. Yours should be an Auburn (cone type). I have an Eaton (clutch type) heavy duty in my 12-bolt. The Eaton website says to use conventional, and that is what the unit is designed for. But both shops that have changed my gears have used synthetic, and I have never had a problem. I have checked Auburn, and I think they say the same thing, but I hear from people all the time that they use synthetic.

The differential accounts for 1/3 - 1/2 of the drivetrain power loss. Synthetic will reduce the loss.
 
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