Gm Synthetic Axle Lube

[pckhalil]

If you could buy the official GM synthetic 75W-90 grape juice for roughly $10-$12 per quart, would you choose this over the after-market brands?

 

Basically...are people choosing Mobil 1/Amsoil/RP/etc. because of the ridiculous cost of the GM stuff, or do people really believe the after-markets are superior to the GM product?

 

I found a source for reasonably priced GM stuff, so cost isn't an issue, I'd just like to choose the best possible axle lubricant. Thoughts?

[csheatz]

I would use AMSoil, since I have a preferred membership the prices are not to bad. The first time I changed the rearend I used Mobile 1 75-90 and now I have come to understand that because I have a G80 I should be using 80-90. I will be using AMSoil 80-90 in the spring when I change it again. Unless I find out the the 75-90 I have in there is going to cause me a issue. Once the AMSoil is in there i should be good as long as I own the truck.... or damn close.

[Bish]

Price for me. I also use Amsoil and it is still less than half the GM price and I'm SURE it is AT LEAST as good if not better than GM. I used Mobil1 in my 01 Tahoe with good luck but have since switched to Amsoil almost everywhere.

[WaterGuy]

Jut did mine with Super Tech synthetic 75W-140.

[Ryan00TJ]

I used M1 75W-90 on my front and rear diffs @ 3K miles. No problems. I have used M1 before in my TJ's Super35 rearend and D30 upfront with great results. Both diffs have lockers and 4.88 gears and have seen alot of hard use offroad. Also used it in my my 7.5" 10 bolt in my Camaro SS that made 420rwhp and did not toast the 10 bolt even with Nitto drag radials. I've also used it in a heavily loaded Mercruiser Alpha SS racing boat outdrive. I'm keeping with what has worked very well for me before.

[dlstewart01]

My GM manual calls for 75W90 synthetic..... GM has used synthetic in the rear diff sinse 1998, open or G80.

 

[Bronc]

75W90 syn. is the correct weight for the G80 Rear. Although the front differential specifies 80-90 conventional based gear oil, the equivelant weight in synthetic is 75-90.

 

Changed mine over to Amsoil Severe Gear 75W90 in the rear and in the front. Both for price and the product.

 

You might want to take a look at the Gear Lube Studyput out. Lots of good info.

[csheatz]

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)

 

This was posed a while back, making me think that we should be using 80W-90 in the rearend.

[dlstewart01]

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)

 

This was posed a while back, making me think that we should be using 80W-90 in the rearend.

 

That was posted so people can see that no additive is needed with a G80. And G80s in trucks are lockers. I don't know the date on this bulletin. GM has used 75W90 synthetic in the rear diff since 1998. Always refer to your owners manual.

[Spurshot]

I've never had any axle problems attributable to the lube. I've never seen any non-racing application where the lube in the axle could be implicated as the problem. That includes standard mineral based gear lubes. I had one vehicle that had a 300+ hp engine and went over 400,000 miles on the little GM axle designed for a 305. Axles have been the least of my problems with non-racing vehicles.

 

Anyone seen problems with gear lubes in standard applications?

[Z45]

fyi..........................

 

 

[pckhalil]

Has anyone worked with the GM stuff? I'm wondering if there is a certain distinctive color to it? i.e. ATF = red, AutoTrac II = blue, etc.?

[Bronc]

The GM 75w90 Syn. Is purple in color and actually has a grape smell too it.

[tanked_darren]

And people have been trying to tell me I need additives in my limited-slip axle, glad to see Im right, (no additives)

[davzog]

75W90 syn. is the correct weight for the G80 Rear. Although the front differential specifies 80-90 conventional based gear oil, the equivelant weight in synthetic is 75-90.

 

Changed mine over to Amsoil Severe Gear 75W90 in the rear and in the front. Both for price and the product.

 

You might want to take a look at the Gear Lube Studyput out. Lots of good info.

 

 

I appreciate this post....lots of really good information. I was expecting it to be geared totally to Amsoil as the winner since it was produced by them....seems pretty unbiased overall and good info.

 

GM does not make gear oil, or motor oil or any other lubricant...everything you buy at a dealership is a rebadged "something else".....my son-in-law's dad works for Conoco Phillips and sees the Ford Motorcraft oil coming off the assembly line all the time...ha

 

There is no doubt that the GM gear oil is high quality, but not any better than others on the market....I used Castrol syntec before I read the article and am pretty pleased with the results....castrol makes pretty good stuff in most cases, but so does Amsoil and Valvoline and Pennzoil....Lucas seems to be a bit less than advertised, but still not bad stuff....

 

For the price difference at Oreilly auto parts, Castrol is working for my HD and I will probably continue to use it...