Gear Lube..?

[randyf]

Is there much differance in 75/90 gear oil vs 75/140?

 

I am changing all the fluids in my 05 Suburban.....

[DBVille]

The 75/140 is thicker. It would cause more friction loss, but might also not protect quite as well in some applications. I use 75/140 in my BMW M3 rear diff, but I would use 75/90 if that's what GM calls for.

[randyf]

The 75/140 is thicker. It would cause more friction loss, but might also not protect quite as well in some applications. I use 75/140 in my BMW M3 rear diff, but I would use 75/90 if that's what GM calls for.

 

 

I know the 140 is thicker......I was going to use the 75/90 in my 05 Suburban if it doesn't really mater.......I'm not sure which one is called for.

[alaska511]

Gm calls for 75w90 in the rear and 80w90 in the front, which is non-synthetic.

 

I have always run 75w90 synthetic front and rear, and my 4x4s have spent half the year in 4wd. I have never had an issue.

[jwhjr]

I run the M1 75-90 front and rear no issues.

[Ryan00TJ]

I run the M1 75-90 front and rear no issues.

 

 

X2

[C. Charles Hahn]

Gm calls for 75w90 in the rear and 80w90 in the front, which is non-synthetic.

 

I have always run 75w90 synthetic front and rear, and my 4x4s have spent half the year in 4wd. I have never had an issue.

 

I do the same, 75w90 synthetic in both differentials. I have used M1 in the past, but right now both of mine are running Royal Purple MaxGear. I've seen no problems with it in either the truck or the Envoy.

[Z45]

GM had been using 75W-90 synthetic front and rear for several years. Synthetic is more fuel efficient and handles the hear better. Yet not all synthetic will be the same.

 

For normal driving a 75W-140 is going to cost you some in fuel economy. Its more appropriate for HD use such as towing. If 75W-90 is to thin for you there is 75W-110 available from some oil companies. If you are using a good Gr. IV synthetic (real synthetic not glorified petroleum) than 75W-90 should be adequate.