Rear Differential Fill On 2008

[01z71]

Its a 2008 4.3L with the automatic transmission. I need to refill the differential and not sure how full to fill it. My '01 you have to be a certain amount below the fill hole but this has the fill hole on the differential cover. Any help is appreciated.

[txab]

Its a 2008 4.3L with the automatic transmission. I need to refill the differential and not sure how full to fill it. My '01 you have to be a certain amount below the fill hole but this has the fill hole on the differential cover. Any help is appreciated.

The Owners manual states about 5/8" to 1 5/8" down from axle housing fill hole. More than likely you fill it 'till it runs out. You might fill it by using the original fill hole then observe the level at the cover fill hole. Filling 'till it is just at the opening will not cause any problems

Edit: Misread your year model.

Thought you had an '02.

 

For your '08, fill by the filler plug on the diff cover. 5/8"-1/5/8" below according to manual. You'll have no problems if you fill it until you can just reach it with your finger. Many people on here do just that and have had zero problems. A little extra lube won't hurt

[01z71]

I may have read that wrong. Is there another fill hole that I didn't see? The fill hole is on the differential cover. I didn't see any other fill holes on the differential.

[txab]

I may have read that wrong. Is there another fill hole that I didn't see? The fill hole is on the differential cover. I didn't see any other fill holes on the differential.

Oops, I looked at your year wrong. for some odd reason I looked and saw 2002 and figured you had an aftermarket cover. An '08 has the plug on the cover. Just fill by that. Again manual shows 5/8" - 1-5/8" below filler plug, or just fill to the filler plug

[01z71]

Okay great thanks. I guess I will leave it a little below the fill plug. Thanks again.

[tanked_darren]

Its a 2008 4.3L with the automatic transmission. I need to refill the differential and not sure how full to fill it. My '01 you have to be a certain amount below the fill hole but this has the fill hole on the differential cover. Any help is appreciated.

The Owners manual states about 5/8" to 1 5/8" down from axle housing fill hole. More than likely you fill it 'till it runs out. You might fill it by using the original fill hole then observe the level at the cover fill hole. Filling 'till it is just at the opening will not cause any problems

Edit: Misread your year model.

Thought you had an '02.

 

For your '08, fill by the filler plug on the diff cover. 5/8"-1/5/8" below according to manual. You'll have no problems if you fill it until you can just reach it with your finger. Many people on here do just that and have had zero problems. A little extra lube won't hurt

 

I may have read that wrong. Is there another fill hole that I didn't see? The fill hole is on the differential cover. I didn't see any other fill holes on the differential.

Oops, I looked at your year wrong. for some odd reason I looked and saw 2002 and figured you had an aftermarket cover. An '08 has the plug on the cover. Just fill by that. Again manual shows 5/8" - 1-5/8" below filler plug, or just fill to the filler plug

 

 

This is INCORRECT for his model, that level is for 6.0L 1500 applications ONLY.

 

It should be 0.04" (1mm) to 0.75" (19mm) from the filler hole.

 

Okay great thanks. I guess I will leave it a little below the fill plug. Thanks again.

 

I used a large clean allen key to measure the level FYI.

[J-man67]

I filled mine until it leaked out. Once the gears move and distribute the fluid, the level should be slightly below the hole.

[dlstewart01]

I have been filling them till it runs out of the hole for over 50 years. Not one failure yet..

[ChevyTech77]

I filled mine until it leaked out. Once the gears move and distribute the fluid, the level should be slightly below the hole.

 

 

I have been filling them till it runs out of the hole for over 50 years. Not one failure yet..

The problem with doing it that way, with the newer diffs, is the fluid may very well blow out the vent tube if

the level is not left just below the fill hole. I too, use a clean allen key to measure the fluid level when refilling.

[dlstewart01]

I filled mine until it leaked out. Once the gears move and distribute the fluid, the level should be slightly below the hole.

 

 

I have been filling them till it runs out of the hole for over 50 years. Not one failure yet..

The problem with doing it that way, with the newer diffs, is the fluid may very well blow out the vent tube if

the level is not left just below the fill hole. I too, use a clean allen key to measure the fluid level when refilling.

 

 

That would be a NO, it will not blow out the vent tube with that little added fluid...

[ChevyTech77]

I filled mine until it leaked out. Once the gears move and distribute the fluid, the level should be slightly below the hole.

 

 

I have been filling them till it runs out of the hole for over 50 years. Not one failure yet..

The problem with doing it that way, with the newer diffs, is the fluid may very well blow out the vent tube if

the level is not left just below the fill hole. I too, use a clean allen key to measure the fluid level when refilling.

 

 

That would be a NO, it will not blow out the vent tube with that little added fluid...

 

O.K. so your's didn't but I've seen quite a few that have. The guy asked for the CORRECT procedure to refill his diff, not YOUR procedure. To each their own. You fill your diff the way you want, I'll fill my customers diffs the way the were intended to be filled. I like to sleep at night, thanks.

[dlstewart01]

I filled mine until it leaked out. Once the gears move and distribute the fluid, the level should be slightly below the hole.

 

 

I have been filling them till it runs out of the hole for over 50 years. Not one failure yet..

The problem with doing it that way, with the newer diffs, is the fluid may very well blow out the vent tube if

the level is not left just below the fill hole. I too, use a clean allen key to measure the fluid level when refilling.

 

 

That would be a NO, it will not blow out the vent tube with that little added fluid...

 

O.K. so your's didn't but I've seen quite a few that have. The guy asked for the CORRECT procedure to refill his diff, not YOUR procedure. To each their own. You fill your diff the way you want, I'll fill my customers diffs the way the were intended to be filled. I like to sleep at night, thanks.

 

 

 

I bought my Mag-hytec rear diff cover 5 years ago. It has extra capacity and a dip stick. I noticed that if I filled to the level within the marks on the dip stick it was over filled about even to the TOP of the fill hole...

 

I called Mag-Hytec and spoke to one of their engineers. he told me that after EXTENSIVE testing that They had come to the conclusion that GM specified too little oil in the rear diff and that it led to overheating and sometimes premature failure.

 

I asked about blowing out the vent hole as well as a an axel seal problem. He stated that in all their testing he had seen NO gear fluid come out the vent tube or a seal failure.

 

I chose to listen to the Mag-Hytec engineer and run the extra fluid. After five tears with towing a camper each summer I can say I have never had a problem I go with what works..and I sleep real well at night.

 

Have a good one...

[ChevyTech77]

I filled mine until it leaked out. Once the gears move and distribute the fluid, the level should be slightly below the hole.

 

 

I have been filling them till it runs out of the hole for over 50 years. Not one failure yet..

The problem with doing it that way, with the newer diffs, is the fluid may very well blow out the vent tube if

the level is not left just below the fill hole. I too, use a clean allen key to measure the fluid level when refilling.

 

 

That would be a NO, it will not blow out the vent tube with that little added fluid...

 

O.K. so your's didn't but I've seen quite a few that have. The guy asked for the CORRECT procedure to refill his diff, not YOUR procedure. To each their own. You fill your diff the way you want, I'll fill my customers diffs the way the were intended to be filled. I like to sleep at night, thanks.

 

 

 

I bought my Mag-hytec rear diff cover 5 years ago. It has extra capacity and a dip stick. i noticed that if I filled to the level within the marks on the dip stick it was over filled about even to the TOP of the fill hole...

 

I called Mag-Hytec and spoke to one of their engineers. he told me that after EXTENSIVE testing that They had come to the conclusion that GM specified too little oil in the rear diff and that it led to overheating and sometimes premature failure.

 

I asked about blowing out the vent hole as well as a an axel seal problem. he stated that in all their testing he had seen NO gear fluid come out the vent tube or a seal failure.

 

I chose to listen to the Mag-Hytec and run the extra fluid. After five tears with towing a camper each summer I can say I have never had a problem I go with what works..

 

Have a good one...

 

You go and believe an "engineer" from an aftermarket parts house, I'll believe the engineers that DESIGNED the axle. Never seen one of the 8.6 axles fail yet from too low of a fluid level, unless of course they were empty due to a leak or it was blowing out of the vent due to OVERFILLING.

 

Same to you.

[MS3DALE]

I also have always filled the axle fluid up to the fill hole in both my GMT800 trucks,and my current '07 GMT900,our techs at the dealership also pretty much fill them up to the fill hole....no issues.

[MS3DALE]

Heres the fluid capacities for both front and rear axles on the GMT900 trucks...

 

Axle Capacities:

 

Front Axle 1000 Series (8.25")

1.43 liters

1.51 quarts

 

Front Axle 2000 Series (9.25")

1.73 liters

1.83 quarts

 

Rear Axle 1000 Series without RPO AXN (8.6")

2.03 liters

2.15 quarts

 

Rear Axle 1000 Series with RPO AXN (9.5" LD)

2.6 liters

2.75 quarts

 

Rear Axle 2000 Series (9.5" HD)

2.6 liters

2.75 quarts

 

Rear Axle 2000 Series with RPO LY6 (10.5" )

2.6 liters

2.75 quarts

 

Rear Axle 2000 Series with RPO LMM (11.5")

3.0 liters

3.17 quarts

 

Rear Axle 3000 Series (11.5")

3.0 liters

3.17 quarts