75W-90 ok for front differential?

[djnelson5460]

Hi all. I have an ‘18 1500 and the Mopar front diff fluid calls for 75W-85, which most part stores dont carry Will a drain and refill of 75W-90 when I change it out cause any issues? Aside from FCA not honoring any warrantee work if something happens of course. Thanks.

 

[Livinalittle]

That’s what I went with. Haven’t had any problems.

Edit: Sorry I didn’t read that correctly, 75W90 for rear diff, 75W140 for front.

 

[Travelin Ram]

IMO the 5 point viscosity difference is immaterial. Probably designed to push consumers into buying Mopar because mass market brands won’t bother to blend it.

I’ve noticed no difference using 90.

 

[PoMansRam]

I've never used the 75w80 or 75w85 recommendations. I always substitute with synthetic 75w90. Usually supertech.

 

[djnelson5460]

Awesome thanks for the replies, I couldnt see the 5 weight difference mattering much but figured Id ask first.

 

[Mister Luck]

things I researched on this subject

2500 and 3500’s use 75w90 in front and rear

75w140 is for severe duty

my take on the recommendation of differential lubricant weight depends on the transmission gearing and whether you have a 6 speed or 8 speed

service manual specs for gear oil are “recommendations” not specified or warranty killers
but you want to stick to details for example friction modifiers or grade of lubricants G-5 etc that are required

https://www.dealers-mopar.com/resources/pdf/chemical/chemical-catalog.pdf

 

[djnelson5460]

Awesome thanks for the info