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Jet-X

Rear Differential Fluid Capacity?

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I'm ordering some Amsoil gear oil but can't seem to locate a spec. on the capacity. The owners manual is useless. :rolleyes: Anyone have a ball park guess on how many quarts to buy? My truck is an '02, 2WD with the limited slip (posi) rear. Thanks...

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Mine is about 2.25 qts so 3 should be plenty. I have the G80 locker. Don't forget, the fill level is aactually below the fill hole. I use an L shaped hex key to measure. If you top it to the fill hole, the seal will eventually start leaking.

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Good advice from above - don't overfill this fluid - follow the guides on this site and use the L-shaped hex key and you'll be just fine.

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Cool.. Thanks for the replies. By the way, do the newer differential's have a drain plug or do I have to remove the cover?

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I really don't see the big deal with overfilling the fluid. you say it will leak out of the fill hole. Well what if you park with your truck facing down a steep hill. and besides, the gear oil is getting sloshed around in there pretty good.

 

I fill mine all the way up and just wrap the plug with teflon tape. never had any trouble with leaks.

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Some have drain plugs and some don't. My 02 has one but a friend of mine bought his truck 6 months later and it has the same options but no drain plug. I can't understand why but there must be a reason. If your lucky yours will have one. Althought I would recommend pulling the cover and cleaning out inside and cleaning off the magnet. Mine had a collection of fuzz on it with only 12k miles on the truck when I switched both front and rear over to the Series 2k oil.

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Some have drain plugs and some don't. My 02 has one but a friend of mine bought his truck 6 months later and it has the same options but no drain plug. I can't understand why but there must be a reason. If your lucky yours will have one. Althought I would recommend pulling the cover and cleaning out inside and cleaning off the magnet. Mine had a collection of fuzz on it with only 12k miles on the truck when I switched both front and rear over to the Series 2k oil.

Good point on the initial service. That is when you'll find a collection of filings on the sheet metal cover magnets. I did mine at 600 miles and again at 1,200 miles. At 1,200, hardly a spec.

 

I've always filled my axle to the fill hole and never a problem. I wonder if GM is admitting to leaks with their pinion seals or axle seals??

 

Mine came with "no charge" leaking pinion seal which the local dealer promptly replaced. I've kept mine topped off and never had a leak since.

 

My owner manual and the Helm shop manual both suggest 2 quarts. That would leave the pinion bearing completely dry and depend on "splash" for lubrication. It will hold about 2.7 quarts.

 

The first time you fill, with the fluid at the fill plug put the plug back in. A week or so later you'll check and discover you can squeeze in about 20 fl oz more. The rest must settle into little nooks and crannies.

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Rear differential oil level for a 1/2 ton, 8.5" ring gear is from

5/8" to 1 5/8" below the fill hole when the oil is cold. You can

find this information in your owners manual.

Personally I fill mine to 1" below the fill hole. Never had a

problem. I to use Amsoil 75W-90.

 

westex

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I really don't see the big deal with overfilling the fluid. you say it will leak out of the fill hole. Well what if you park with your truck facing down a steep hill. and besides, the gear oil is getting sloshed around in there pretty good.

 

I fill mine all the way up and just wrap the plug with teflon tape. never had any trouble with leaks.

It's not that it leaks out the filler hole. It will start leaking at the seal where the driveshaft enters the differential. Not a fun repair especially if you caused it by overfilling.

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that is interesting thanks for the info bish. but wouldn't the fluid still slosh around causing it to leak out.

 

just a thought. I am sure that the owner's manual and the Helm aren't wrong and you aren't in danger of underlubricatating but I feel that if it is going to leak overfilling the diff won't be the cause.

 

JMO.

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this is the actual capacities per the helms manual

 

Axle

Rear 8.6 Ring Gear 2.0 Liters 2.1 Quarts

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I still for the life of me can't figure out why GM wants the rear axle kept that low on the 1500's. If you carefully measure down, with the fluid at the "recommended" level the pinion bearing is high-n-dry and will have to depend on splash for lubrication.

 

The 1500HD, 2500LD, 2500HD, and 3500 all recommend the rear axle fluid level to be kept flush with the fill hole. The 1500HD and 2500LD axles are "heavier duty" than the 1500LD, but are still the semi-floating design. The 2500HD and 3500 axles use full-floating wheel support.

 

My 1500 came from the factory with a leaky pinion seal on the rear axle. I noticed this the very next day when I backed out of my garage. The GM dealer promptly fixed it.

 

I've always kept my rear axle "topped off" and have never had a leak. Some folks have commented that if you don't keep the fluid low, the excess will be forced out the vent tube.

 

I don't buy that either. Synthetic gear oils are MUCH more thermally stable than mineral-based gear lubes, so there is much less of this expansion. I'm sure I would have noticed excess fluid after towing +7,200 lbs, nothing.

 

FYI the vent tube is routed to just under the gas fill. If it did pee out, you'd have gear oil all over your gas cap.

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The company that made that rear end put the fill line where they think it should be, Gm decided they liked it below that. Welll seeing as how GM has enough trouble keeping my engine from Knocking, I think I will follow the manufactures recommendations ( The real manufacturer ) Anyways older trucks that what ya did filled to the top and let it seep out. My 2000 with the 3.73 No locker takes a little under 3 to fill it. In case anyone is wondering it has held up very good 20k and not a problem. I'm gonna have to take the cover off sometime and see what the insides look like when it gets warm.

 

As for fluids, I like the GM stuff seems to work fine and I would be more worried about the oil you use than the level it's at. Anyways :withstupid

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