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Discussion Starter · #1 ·
I had my rear differential rebuilt by a friend, but he didn't put in the differential fluid. I went to fill it up and I popped the cap off the breather. Does that whole plastic piece pop out? Does it twist out? I don't want to break it off so I figured I'd go against my usual judgement and ask first! Also, how do you know its full? Do you just fill it until the cap overflows?
 

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Auto...carefully "pop" the breather cap back on. Look on the passenger (right) side of the pumpkin. There should be a plug with a square head sticking out the side. Unscrew that plug and fill the diff. with gear oil until it starts drooling out. Re-install the plug. If this is a posi. make sure to use a GL-5 type of gear oil as well as a friction modifier. I hope your "friend" gave you break in instructions. Drive around town "normally" for about ten miles and then park the car for at least a 1/2 hour before driving it again. Re-check your oil level. Good luck.:thumbsup:
 

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Discussion Starter · #4 ·
Thanks guys. Good thing I asked. I didn't even notice that plug. I had an Eaton Posi installed and the tech at Summit recommended I buy 3 quarts of Lakewood BFL 80W90. At $12 a quart I hope thats good stuff. He didn't mention anything about a friction modifier. Is that something I can pick up at any car parts store?
 

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Twelve dollars a quart for GEAR LUBE? Don't waste your money, any 90 weight gear lube will work fine as long as you put a tube of limited slip additive in with it. I run an Eaton posi as well and it's been trouble free on no name gear lube @ $5 a gallon.

Tom
 

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1 tube of whale sperm (LSD additive) 4.95, 2 quarts of 85/90 gear lube 2.00 bucks a quart at your local autozone. DO NOT USE SYNTHETIC OIL with a clutch type posi. Screw the tech (salesman) at summit. They are inherently clueless. They didn't use 12 dollar a quart gear lube 40 years ago, and yet they
still function quite well after all that time with cheap gear oil.
 

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You are right about syn. lube. The tech. at Eaton told me to use a good grade 80 90 and a bottle of Posi add. Take the car out ,drive it, make about 10 figure 8s in a parking lot, and you should be good for 40 to 45 years. NO syn. lube!
 
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