Are thicker gear oils better for differentials?

[FTTSHO]

I’m getting ready to change my differential fluids (front and rear) on my 2001 Chevy Blazer 4door 4x4.

Right now I have Supertech 80w90 Dino gear oil in the front and rear diffs, which I put in about a year ago. There’s no noise from the differentials, so they are in good shape.

I just want to drain the diffs out and put some new fluid in, because last time I drained the diff fluids, the fluid had some metal in it, and it was black, from the previous owner.

Just trying to do some preventative maintenance, just to get the remaining metal out of the diffs!

So would thicker gear oils better protect my differentials?

I’m thinking of switching to synthetic 75w-110 from the recommended 75w90/80w90


Do thicker gear oils provide better diff protection, like thicker engine oils do in engines?

 

[JavierH19]

Yes thicker oil more film thickness to prevent friction though one would say they don't help if you're not towing and loading it but I still put 140 in my old trucks that still have the original differentials. I imagine they have some wear though I don't know so I'll just use thick oil too help it some. At worst I hurt my mpg by a decimal amount.

 

[LDM]

Simple answer is yes but on an 01 Blazer I doubt you are going to be doing anything with it that requires thicker oil. The 4.3 isn't a super powerful engine and the S10 Blazer was never suppose to tow heavy loads. I'd run some 75w90 synthetic in both and call it a day or if you want to save a few $$$ then just continue to use 80w90 like you have been.

 

[dnewton3]

It's not as simple as "is this better?" ...

Mainly because you need to define several things for us to understand what "better" means to you, so we can make a good recommendation.
- the application (we've been given a little bit)
- the use (DD; towing; what else?)
- the environment (how hot or cold are your temp extremes?)
- the OCI (how often will you change it? miles?)
- syns or conventional oils?
- is fuel economy a concern? (thicker oils consume energy)

Generally, if you pick something off the PRI QPL you'd have good performance and wear protection.
See the sticky thread at the top of this forum.

 

[FTTSHO]

It's not as simple as "is this better?" ...

Mainly because you need to define several things for us to understand what "better" means to you, so we can make a good recommendation.
- the application (we've been given a little bit)
- the use (DD; towing; what else?)
- the environment (how hot or cold are your temp extremes?)
- the OCI (how often will you change it? miles?)
- syns or conventional oils?
- is fuel economy a concern? (thicker oils consume energy)

Generally, if you pick something off the PRI QPL you'd have good performance and wear protection.
See the sticky thread at the top of this forum.

-Application is daily driving. Mostly highway.
- No towing. Just occasionally moving around about 500lbs worth of stuff inside the car with 4 people traveling 200-300miles, and driving about 80mph down the highway.
- I live in South Carolina, so it doesn’t ever go below 28F, but it does go above 100F during the summer.
- I plan on changing the diff fluids every 40,000 miles.
- I want to switch to synthetic diff fluids
- Fuel economy is not a concern. I got a Severe duty fan clutch, and the truck gets bad fuel economy already.

I just want the best for my truck. It’s got 108k miles on it right now and I want everything to last as long as possible. I plan on keeping this thing at least for another 200k miles, because I dont want car payments.

Just want to know if 90w is the best choice for longevity.

 

[BAJA_05]

Not a recommendation on what gear oil brand -- but I can tell you -- the squeeze pack quarts are very easy peasy to use on differentials and transfer cases. I went with Valvoline Synpower 75W90 squeeze pack quarts on my front differential and transfer case most recently with my Tundra.

 

[4WD]

Not a recommendation on what gear oil brand -- but I can tell you -- the squeeze pack quarts are very easy peasy to use on differentials and transfer cases. I went with Valvoline Synpower 75W90 on my front differential and transfer case most recently with my Tundra.

Yeah, just put in some Amsoil SG and kept the bags

 

[BAJA_05]

Yeah, just put in some Amsoil SG and kept the bags

Great idea bud!

 

[edyvw]

Great idea bud!

Run authenticity check at SKF web site

 

[BAJA_05]

Run authenticity check at SKF web site

Truck with part is at garage waiting for Monday install.

 

[Pablo]

I’m getting ready to change my differential fluids (front and rear) on my 2001 Chevy Blazer 4door 4x4.

Right now I have Supertech 80w90 Dino gear oil in the front and rear diffs, which I put in about a year ago. There’s no noise from the differentials, so they are in good shape.

I just want to drain the diffs out and put some new fluid in, because last time I drained the diff fluids, the fluid had some metal in it, and it was black, from the previous owner.

Just trying to do some preventative maintenance, just to get the remaining metal out of the diffs!

So would thicker gear oils better protect my differentials?

I’m thinking of switching to synthetic 75w-110 from the recommended 75w90/80w90


Do thicker gear oils provide better diff protection, like thicker engine oils do in engines?

In general yes. The reasonable argument doesn’t need to get really deep when you look at

​

Automotive Lubricant Viscosity Grades: Gear Oils – J 306​

And see that the old SAE 90 gear oil viscosity range was divided in two. New 110 is really just the upper end of the earlier SAE 90 viscosity range

 

[barkingspider]

80w90 every 40k miles sounds good, if you want syn, 75w90 is fine. No need for heavier than that

 

[21_6.7f450]

I use 75w140 Redline in every differential (6) in 3 trucks and have no issues and very little black goop on the magnets. I'd wager 75w110 isn't going to hurt anything. Might even help the little 10 bolt. I say as a general guide, for a truck or RWD SUV, with that usage I might go a bit thicker but not thinner in my area...your area sounds similar.
Go for 75w110. It might drop the fuel mileage from 16mpg to 15.99995mpg. Nothing in reality for you.

 

[D60]

On rear axles I worry a bit about flowing to the wheel bearings in cold temps.

For a cute ute I'd stay with a 75W-90 or 80W-90, but in truth it doesn't matter.

 

[AP9]

Consensus is that GM B platform cars generally do better with a conventional 80W90 than a synthetic 75W90, whether it's got the G80 Posi or not. The 80W90s will have higher viscosity under most driving conditions; differential oil spends less of its life at 100+°C than engine oil ever will, possibly never in some cases.

 

[21_6.7f450]

Go all out and put 75w140 in it.
With 500lbs and 4 adults on board, that severe duty for a little 10 bolt. You are at or over payload with that load.