Why oh why do they do this? 75w85 recommended but not popular on the shelf.

F

Fishstyx

Joined
Sep 28, 2023
Messages
249
Ok two questions.
1) why do manufacturers like Stellantis who manufacture Ram and Jeep call for 75W85 in the front and rear diffs? When it’s not a popular viscosity gear oil thats readily available at Walmart, Amazon, tractor supply etc..,
2) can one use 75w90 in substituting it for 75W85? Because my Ram 2500 is due for its gear oil change.
Thanks
Oh and I know red line sells it at 24 dollars per quart not sure if I want to pay dealership price for gear oil.
 
Fishstyx said:
Ok two questions.
1) why do manufacturers like Stellantis who manufacture Ram and Jeep call for 75W85 in the front and rear diffs? When it’s not a popular viscosity gear oil thats readily available at Walmart, Amazon, tractor supply etc..,
2) can one use 75w90 in substituting it for 75W85? Because my Ram 2500 is due for its gear oil change.
Thanks
Oh and I know red line sells it at 24 dollars per quart not sure if I want to pay dealership price for gear oil.
Click to expand...
OEMs do it so they can sell you their “own” gear oils for absurd prices. Yes, 75w90 gear oils that meet spec work well.
 
Fishstyx said:
Ok two questions.
1) why do manufacturers like Stellantis who manufacture Ram and Jeep call for 75W85 in the front and rear diffs? When it’s not a popular viscosity gear oil thats readily available at Walmart, Amazon, tractor supply etc..,
2) can one use 75w90 in substituting it for 75W85? Because my Ram 2500 is due for its gear oil change.
Thanks
Oh and I know red line sells it at 24 dollars per quart not sure if I want to pay dealership price for gear oil.
Click to expand...
Honda specs it as well in several of their MT models sold in India given it is a MT gear oil. What I can say is that with w90, you end up with heavier and notchier shifts, it is slick and fast shifting with w85. Not entirely sure that's going to be as germane in a differential.
 
Ah, the old force you to buy OE/dealership conspiracy. They do it to reduce fleet mileage stats.
The question should be: "Why don't the major gear oil manufacturers offer it in OTS products and why don't the chains and box stores carry it?"
 
CleanSump said:
Ah, the old force you to buy OE/dealership conspiracy. They do it to reduce fleet mileage stats.
The question should be: "Why don't the major gear oil manufacturers offer it in OTS products and why don't the chains and box stores carry it?"
Click to expand...
You and I both know that the OEMs absolutely want you to buy their own lubricants. If there was a legitimate need for 75w85, the gear oil manufacturers would be making it widely.
 
CarbonToast said:
If towing heavy better swap in 75w140 or your pinion bearings will only live 75k-100k miles.
Click to expand...
Is this specific to the Ram differentials? I tow heavy and so does my dad. 167k on my dad’s with the factory fill (yes, he has never changed it) and 135k on my truck with Amsoil Severe Gear 75w90.
 
First world problems.
you can do 2 things
1.use 75w90.. no issues.
2. source 75w85 from OEM, hpl, amsoil, redline, motul, etc.

I ordered hpl but if I hadn't valvoline squeeze bags are EZ mode.
 
brandon9715 said:
Is this specific to the Ram differentials? I tow heavy and so does my dad. 167k on my dad’s with the factory fill (yes, he has never changed it) and 135k on my truck with Amsoil Severe Gear 75w90.
Click to expand...
My expirence is with half tons F150s and this is the general guidance. My rear end quieted down after switching and a friend had cooked his 8.8 by 90k miles, but he was on factory fill and towed heavy for alot of miles.
 
While my post doesn't have anything to do with trucks, it makes you wonder. My old Harley motorcycle's manual says to use 20w50 wt engine oil in it's transmission. But Harley also sold an oil for transmission use, that has been tested on this site, to be pretty much just straight 40 weight oil. And recently they've come out with a 85w140 weight oil for use in the transmission. That's a pretty big spread of oil weights, that at some point were all acceptable for use in their motorcycles wouldn't you say?. All those oils are available at your local Harley dealer , for stupidly high prices. I myself have been using auto store brand 75/90 wt gear oil in my bikes for years without any issues. Engine oils included. And it hasn't been proven to me that using dealer marketed oils do anything more than aftermarket brands. One other thing, I haven't used dexos oil in my wife's equinox in over 65k miles. What exactly is that supposed to do to engine oil ?.,,
 
Fishstyx said:
Ok two questions.
1) why do manufacturers like Stellantis who manufacture Ram and Jeep call for 75W85 in the front and rear diffs? When it’s not a popular viscosity gear oil thats readily available at Walmart, Amazon, tractor supply etc..,
2) can one use 75w90 in substituting it for 75W85? Because my Ram 2500 is due for its gear oil change.
Thanks
Oh and I know red line sells it at 24 dollars per quart not sure if I want to pay dealership price for gear oil.
Click to expand...
FWIW, I have been using 75w90 in my front and rear diff in my Ram 2500 since I bought it in 2016. It spent a decent amount of time towing an 11K TT
 
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