Differential and Transmission Service

[RoGuE]

I'm getting ready to these this weekend on the 2002 Suburban with 103k miles. For the transmission, I am just doing a pan drop and fluid change. It was last done at 60k miles when the torque converter was replaced.

What is a good fluid to use here?

How much should I expect to have to refill it by only dropping the pan?


As for the differential, I was just planning on using the drain plug, but I see a lot of people also remove the cover to clean out a magnet. Is this critical to do?

And how much oil does the differential take? And what is a good oil to use?

Thanks

 

[defektes]

Differential is easy to do. If you do a drain and fill just dump it when its hot (carefull it can burn.) loosen the filler plug first!!! Then drain it all out, start pumping the fluid in till it begins to come out of the fill plug, then replace the fill plug. I use Valvoline syn 75-90 gear oil in my 2002 Sierra. You can also use Dino gear oil too, just change it out more often.

For the transmission I would measure how much you drained with empty oil containers and fill with the same amount. As for the type I do not know.

Have fun.

 

[Nayov]

I could swear the transmissions on those things had a plug. I'm quite sure the '01 we had at work did.

 

[Trav]

Don't forget the limited slip additive if it has a limited slip rear end.If its a 4 wheel or AWD it probably does.

 

[RoGuE]

Originally Posted By: Nayov
I could swear the transmissions on those things had a plug. I'm quite sure the '01 we had at work did.


It does have a drain plug but I also need to change the filter.

Originally Posted By: Trav
Don't forget the limited slip additive if it has a limited slip rear end.If its a 4 wheel or AWD it probably does.


Nope, just a 2 wheel drive.

 

[saberz]

Make sure you can undue the fill plug before undoing the drain plug. That is always rule number one.

Typically on most cars/trucks I've owned the drain plug is the magnet itself. The Xterra had a bunch of grease esque diff fluid on the plug with some material on it(factory fill, 5 years 32k). Cleaned it 100% and sealed her up with Mobil 1 synthetic diff fluid.

 

[stenerson]

Are you gonna change the filters while the pan is down? (if it has filters)

 

[RoGuE]

Originally Posted By: Anies
Make sure you can undue the fill plug before undoing the drain plug. That is always rule number one.

Typically on most cars/trucks I've owned the drain plug is the magnet itself. The Xterra had a bunch of grease esque diff fluid on the plug with some material on it(factory fill, 5 years 32k). Cleaned it 100% and sealed her up with Mobil 1 synthetic diff fluid.


I think I read that there is a magnet on the inside of the cover.

Originally Posted By: stenerson
Are you gonna change the filters while the pan is down? (if it has filters)

Yep.


Does anyone know the best place to buy the transmission filter? Or are the diff (if I remove the cover) and trans gaskets reusable?

 

[silverrat]

Originally Posted By: defektes
Differential is easy to do. If you do a drain and fill just dump it when its hot (carefull it can burn.) loosen the filler plug first!!!


I have never seen gear oil come out of a differential that is hot enough to burn. When does this happen?

 

[AzFireGuy79]

Just switched two trucks over to Dexron VI with GREAT results! The first was my sisters 02 Yukon Denali with 65K and the second was my dads 00 Silverado 1500 113K. I opted to perform a cooler line fluid exchange on both, along with removing the pan and changing the filter (I do this on every exchange I do regardless of miles). I used redline D6 on the Yukon and Supertech Dexron VI on the Silverado. Drain and refills are a waste of time and fluid. To get the full benefit, you need to get all of the old fluid out. Drains usually purge less than 30%.

Both trucks shift 100% better with the Dex VI. Very happy with my decision to go away from Dex III. As far as the diff is concerned, I used Mobil 1 on the Yukon and Valvoline on the Silverado. Nothing exceptional to report as would be expected. Usually, I only use Redline or amsoil gear oil, but I did not have any on hand this time.

As far as the diff gasket goes,no its a traditional style and needs to be scraped off and either replaced with another or you can use permatex The Right Stuff which is very good or regular old black RTV. There is a round magnet on the inside of the pan that needs to be cleaned. It is glued on. I like to buy my transmission filters at NAPA. They are high quality and usually come with a good gasket Neoprene/Rubber style. Cork gaskets should be avoided like the plague!

One last thing, one these trucks the drain plug will usually strip due to a very shallow head ( terrible design that GM has addressed with a new style plug). I use vise grips to get them off. Give it a try. No worries if you cant get it off you can just loosen the bolts from the front to back and drain it partially until you can support and remove it completely. Good luck and let us know how it goes!

 

[RoGuE]

Do you have specific instructions on how to do a full AT fluid exchange?

Do I have to remove the cover of the diff then or can I just drain it? It was last done at 60k by the dealer so I don't know if there would be much metal saving on the magnet at that point anyway.

Originally Posted By: AzFireGuy79

One last thing, one these trucks the drain plug will usually strip due to a very shallow head ( terrible design that GM has addressed with a new style plug). I use vise grips to get them off. Give it a try. No worries if you cant get it off you can just loosen the bolts from the front to back and drain it partially until you can support and remove it completely


Are you referring to the trans pan drain plug?

 

[AzFireGuy79]

Sure I will PM you tonight as far as the step by step flushing instructions go for this truck. Concerning the diff service, I would just drain it seeing as it was serviced not too long ago. The magnet has a pretty good capacity( it's a large donut style). No worries there.

The drain plug I was referencing is the one on the transmission pan. Its not only a very shallow head that makes it tough, but its recessed into the pan. Terrible design. GM engineers

. As I mentioned they do have a revised plug for it now.

You will be glad you performed a full fluid exchange. It's really the best way to service most all transmissions especially when upgrading fluids. You will love the Dexron VI. And the cool thing about it is that if it's licensed they have to follow a pretty strict formulation. Supertech is more than adequate and is fairly economical at $3.77 per quart.

 

[endeavor to persevere]

Don't forget the limited slip additive if it has a limited slip rear end.If its a 4 wheel or AWD it probably does.
--------------------------------------------------------------------------------------------

GM trucks and SUVs did not come with a limited slip. With the exception of the Quadrasteer which did come with a G86 limited slip. They came with a G80 locking diff. GM says not to put an additive in the G80 locker as it will delay the locking and could damage the unit. I can show a GM bullitan if you need it.

Also GM has used synthetic in the rear diff since 1998.
\
And +1 on the Dexron V1.

 

[wgtoys]

I like Mobil-1 75W-90LS differential fluid because it already is compatible with conventional or limited slip diffs right out of the bottle. Oddly enough, Mobil-1 is cheaper than Valvoline Synthetic 75W-90 at our local O'Reilly.

 

[mechanicx]

Originally Posted By: AzFireGuy79
Sure I will PM you tonight as far as the step by step flushing instructions go for this truck. Concerning the diff service, I would just drain it seeing as it was serviced not too long ago. The magnet has a pretty good capacity( it's a large donut style). No worries there.

The drain plug I was referencing is the one on the transmission pan. Its not only a very shallow head that makes it tough, but its recessed into the pan. Terrible design. GM engineers

. As I mentioned they do have a revised plug for it now.

You will be glad you performed a full fluid exchange. It's really the best way to service most all transmissions especially when upgrading fluids. You will love the Dexron VI. And the cool thing about it is that if it's licensed they have to follow a pretty strict formulation. Supertech is more than adequate and is fairly economical at $3.77 per quart.


I agree with you that Dex VI is the best and only way to go now. I wished Walmart would keep it in stock. the cheapestg I've seen it anywere else is like $6-7 qrt. And it's not available in the gal size. 12 qts or so would not be cheap.

I also like to flush all the old out. I don't have or trust flush machines. I'd like to hear your flush procedure, although I don't have a truck. I assume you unhook the low pressure line at the trans cooler so as to also flush the cooler?

 

[RoGuE]

Originally Posted By: AzFireGuy79
Concerning the diff service, I would just drain it seeing as it was serviced not too long ago. The magnet has a pretty good capacity( it's a large donut style). No worries there.


I looked through the dealer records and they say at 30k a "diff service" was done and at 60k a flush was done...I should still be good with only a flush on this?

 

[AzFireGuy79]

If the diff was last serviced at 30K I would say its a good idea to remove the cover and inspect/clean the magnet. The "flush" must be in reference to something else unless the service records specifically indicate it was the diff. The only ways to flush one would be adding a chemical or ester and driving it, spraying it out with brake kleen!? Usually dealers drain and fill. Most only flush the trans if specifically asked (GM especially). Could it have been the brakes or P/S system?

My rule on GM diffs with drain plugs is if its been more than 40K or I am switching oil types then I will always pull the cover and clean the magnet, cover and inside of the case. Most of the units that I have serviced at 60K that had a prior service at 30K looks very clean. So unless something out of the norm as far as wear is concerned takes place you would be good to go. Everyone is different on these. Many go 100 or 150K without any changes and are still truckin. So whatever you choose will be an improvement over 90% of others on the road.

 

[ctc]

I just bought an 05 Yukon XL Denali w/ AWD. LSD or no?

I'm going to be changing all drive train fluids soon.

 

[endeavor to persevere]

Originally Posted By: ctc
I just bought an 05 Yukon XL Denali w/ AWD. LSD or no?

I'm going to be changing all drive train fluids soon.


LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849). The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.
VEHICLES/COMPONENTS INVOLVED: ----------------------------- Some light duty trucks equipped with locking rear axles, RPO G80.
SERVICE PARTS INFORMATION:
Part Number Description ----------- ------------------ 10950849 Lubricant, Rear Axle (1 litre)
Parts are currently available through CANSPO.
WARRANTY INFORMATION:
As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
© Copyright General Motors Corporation. All Rights Reserved.

 

[ctc]

Sorry if this is a dumb question. Does the AWD use the G80 rear diff?