Mobil synthetic 75W-90 in a G80 Locking diff

[esox07]

2013 Chevy Silverado 1500 with a G80 Locking Differential.
I changed out my diffs at about 40,000 miles and that was a year ago. I am at 61,000 miles now. The stuff I put in was: Mobil synthetic 75W90. But, I didn't realize it had an "LS" on the end of the product name. I am unsure if the stuff actually includes the Limited Slip additives or if it is just compatible with an LS differential. My owners manual states to NOT use a limited slip additive in my G80 Locking diff. Did I make a mistake??? Do I need to change them out again with another product?

https://www.amazon.com/Mobil-104361-75W-...;keywords=75w90

 

[kschachn]

From the PDS:

Quote:
Mobil 1 Syn Gear Lube LS 75W-90 combines wax-free synthesized hydrocarbon base oils and a specially designed extreme-pressure, limited-slip, sulfur-phosphorous additive system to help provide a significantly higher level of performance in rear axles and differentials versus conventional fluids

 

[esox07]

[censored], thanks, I guess I need to get myself some non LS lube and change it out.
Thank you very much kschachn.

 

[kschachn]

No problem. One wonders what the issue is, since you've gone a year already.

You may have a problem finding the Mobil product that isn't LS. I changed out the diff fluid in my BMW a few months ago, and all anyone had was the LS variety. On mine it didn't make any difference though. I think my local NAPA sells the non-LS variant of an Amsoil product, I used that prior to this change and it worked fine.

 

[esox07]

yah, i wonder what the amsoil price per quart is though?

 

[4WD]

I ran M1 (LS) oil in a couple GM G80's for 200k total in previous trucks.
I ran it 50k in my current G80 and it came out like new.
I put Delvac synthetic back in (now Delvac 1) and Mobil 1 in the front ...

 

[Stewart Fan]

The M1 you're currently using is fine for the G80 in your truck. The reason GM doesn't recommend adding any friction modifier is that the OEM fluid already contains a friction modifier and nothing more is needed.

There are thousands of people running M1 in their trucks equipped with a G80. I've used M1 in 3 different G80 equipped trucks.

I'm currently using Amsoil Severe Gear which also contains a friction modifier.

 

[esox07]

Thanks guys, maybe I will hold out, but I know that AMSOIL specifically states it is compatible with locking differentials. I don't understand why Valvoline and Mobil don't do the same. I don't like playing in the gray area when it comes to my truck.

 

[4WD]

07/17/11 quote said AAM set up the standard and you could expect the (Texaco) OEM to darken ...
(The factory oil did - M1 does not) ...
LS "is not needed" - but no warning there ... or my OM ...

 

[donnyj08]

I've had synpower 75w90 LS fluid in Mine for 50k miles so far. it works perfect. I'm about due to change it out again now.

 

[4WD]

The other interesting comment in the Eaton guys G80 feedback was heat is from the gears and their kit does not add heat to the gear lubricant ...

 

[aquariuscsm]

Probably need to swing by the GM dealership and get some oem fluid,

 

[barkingspider]

I used supertech 75w90 in my old 04 silverado w g80, worked perfect. I have delo 75w90 in my escalade front and rear diffs and it works perfect. Both fluids do not have the LS in it. Regardless, M1 w LS is fine in a g80

 

[esox07]

I haven't had any issues in my diff so far. I think I will just be waiting to swap it out with some Amsoil Long Life at the next scheduled change. I half way through my 40,000 mile change interval.

 

[umungus1122]

Originally Posted By: Stewart Fan
The M1 you're currently using is fine for the G80 in your truck. The reason GM doesn't recommend adding any friction modifier is that the OEM fluid already contains a friction modifier and nothing more is needed.

There are thousands of people running M1 in their trucks equipped with a G80. I've used M1 in 3 different G80 equipped trucks.

I'm currently using Amsoil Severe Gear which also contains a friction modifier.
This. There's absolutely no reason to change the fluid.

 

[esox07]

Thanks for the vote of confidence. I am relieved to know that I likely haven't done any damage to my differentials, but I think I will go with AMSOIL Long Life 75W90 at my next change just for peace of mind.

 

[kschachn]

Originally Posted By: esox07
yah, i wonder what the amsoil price per quart is though?


It wasn't bad, comparable to the M1 price IIRC. I use their gear oil in my ECHO too.

 

[wtd]

Years ago I used Mobil 1 diff fluid in the rear diff of my 98 chevy K1500. At about 55,000 miles I started to get some rear end whine. At about 75,000 miles it got bad enough that I had it checked out and it was discovered that my pinion and carrier bearings were shot. This was on a truck that hardly ever hauled anything or pulled a trailer. Never anything heavy.

After the repair I went back to a conventional diff oil and have not had any problems since. I'm not saying that Mobil 1 was to blame but it didn't make me want to use it again.

Wayne

 

[esox07]

I am probably going to swap it out this next summer. It will have about 30,000 on the current mobil gear lube. I am thinking about going with Amsoil. Anyone have any thoughts on this? I can't find anywhere that says it DOES NOT specifically contain any LS additives. But it seems the guys on Silveradosierra.com like it a lot for our G80 rear ends.

 

[jhellwig]

There is nothing in a g80 rear end that a limited slip additive is going to affect. The g80 has a mechanical lock that locks the axles together when one is spinning faster than the other. That is why they make a clunk. When this system came out it was called Gov Lock but got nicknamed Gov Bomb due to the tendency to grenade in the days before traction control and torque management.