Wrong gear oil for diesel pusher

[Mark Brandt]

I ordered a case of Mobil 1 75w-140 GL-5 gear oil for use in the rear axle of our '04 diesel pusher (Freightliner XC chassis) motorhome. The mechanic filled the diff before noticing that the oil is labeled Light Truck & SUV. The Amazon listing did not have that info, unless you enlarge the photo of the product enough to read the label.

The axle specs call for 75 or 80w-90 or 140 weight. Most of the time we are pulling about 8500 lbs with our 25,000 lb rv, which is comfortably below the GVWR. The weight we tow pushed me towards a 140 gear oil.

I hate to dump $100 worth of oil, but it seems the only option unless 140w light truck would provide the same level of protection as a 90w heavy truck oil.

We live in a rural area, and I'm having a hard time finding a name brand 75, 80 or 85w-140 Full Synthetic gear oil from the usual good value online sources (Amazon, Walmart, etc). I need 7 quarts, so buying a pail is out of the question.

Amazon offers Valvoline Advanced Full Synthetic 75w-140 that is GL-5 and SAE J2360, but the Meritor list of approved oils lists Valvoline HD Full Synthetic with EP.

Any suggestions as far as an online source of heavy truck gear oils?

 

[Bailes1992]

GL-5 is the specification for hypoid differentials. You'll be fine.

 

[burbguy82]

I run 75w140 in my RV rear end aswell. I think i used Valvoline this time, but i would not hesitate to use 85w140 Mobillube HD conventional, or 80w90 either. Your M1 choice is fine, not sure why you think is would not be.

 

[NiwradND]

It's all the same, it's the same lube that the 18 wheelers run in the big semis pulling loads weighing 150,000 pounds.

 

[dnewton3]

The axle specs call for 75 or 80w-90 or 140 weight. Most of the time we are pulling about 8500 lbs with our 25,000 lb rv, which is comfortably below the GVWR. The weight we tow pushed me towards a 140 gear oil.

What does the OEM chassis manual say about API rating? I would presume it calls for GL-5? If so, what you got will be fine. Certainly, when using an RV to tow additional weight, the 140 grade is preferred.

Amazon offers Valvoline Advanced Full Synthetic 75w-140 that is GL-5 and SAE J2360, but the Meritor list of approved oils lists Valvoline HD Full Synthetic with EP.

Some of the OE chassis makers do have specific recommendations. I'm not really sure that these criteria matter in your case, but again, what does the OE chassis manual say?

 

[64bawagon]

Walmart online usually lists M1 in several flavor in gallon jugs. It does not sound like the specs are all that picky. We ran M1 75W90 in everything from staff pickups/tahoes to tandem axle aerials.

 

[JavierH19]

That light whatever wording doesn't matter one bit. Synthetic 140 grade gl5 is synthetic 140 grade gl5. You're perfectly good.

 

[Pablo]

I don't understand the problem(?) am I missing something? (I HOPE this is not ANOTHER TROLL post)

 

[Mark Brandt]

dnewton3 asked what the chassis manufacturer (Freightliner) requires. I skipped that step when I saw that a few different rear axles with different capacities are used in the XC chassis. I identified my axle and went to the Meritor specs. Meritor calls for GL-5 & J2360, which appears to be a mil spec, and lists specific oils to avoid any warranty issues.

With most everyone saying the M1 I have is fine, I backtracked to the Freightliner "spec": Hypoid 75w-90. It doesn't even say GL-5, so that made me chuckle.

The J2360 rating is what made me think I should drain and start over.

I appreciate the input. Unless someone has second thoughts or someone new posts to the contrary, I'll roll with the M1 Lt Truck & SUV oil and pull a sample next summer after ~ 6,000 miles.

Thanks again! I'm more in tune with high performance racing oils than heavy duty equipment.

 

[Japanese]

I don't understand the problem(?) am I missing something? (I HOPE this is not ANOTHER TROLL post)

He worries because in the description of M1 75W-140 says:
"... automotive gear performance vehicles like sport utility vehicles, vans and light duty trucks"
However, it says also "multi-purpose".
https://www.mobil.com/en/lubricants...cts/products/mobil-1-syn-gear-lube-ls-75w-140

But it doesn't say heavy duty or commercial use.

 

[johnmyster]

Typical 80w-90 is actually not as high of pedigree vs the oil you purchased.

The viscosity difference will not be problematic, perhaps beneficial.

Full send. Run it 30k without a second thought.