Different weight gear oil

MountaineerTom

LJ Enthusiast, Retired USAF Weapons Loader
Supporting Member
Ride of the Month Winner
Joined
Sep 25, 2018
Messages
4,308
Location
Sumter, SC
I know the owners manual doesn't call for this weight, but would there be any adverse effects of using Valvoline conventional 85w-140 for limited slip in my rear dana 44?

I have a Torq Masters automatic locker in the front and they recommended 85w-140 to help quiet down the ratcheting noise. If I can run the same in the rear axle, I only need to carry one kind of oil with me on off road trips.
 
OP
MountaineerTom

MountaineerTom

LJ Enthusiast, Retired USAF Weapons Loader
Supporting Member
Ride of the Month Winner
Joined
Sep 25, 2018
Messages
4,308
Location
Sumter, SC
Great, thank you both.

That leads to my next question. I’ve seen lots of gear oils that say for limited slip but on the back of the bottles is may say something like Limited Slip for top off only. What exactly do they mean by that? What else are you supposed to fill it with if you doing an entire fluid change?

Use friction modifier anyway?
 

machoheadgames

LED turn signal club
Supporting Member
Joined
Jan 21, 2021
Messages
1,038
Location
Dallas, TX
Great, thank you both.

That leads to my next question. I’ve seen lots of gear oils that say for limited slip but on the back of the bottles is may say something like Limited Slip for top off only. What exactly do they mean by that? What else are you supposed to fill it with if you doing an entire fluid change?

Use friction modifier anyway?

Limited slip additive is for clutch style limited slips, like the factory Trak-Lok. Those need friction modifier to work properly. Fluids that say for top off only, likely don't have any limited slip additive in them. Fluids that do have it will say they're compatible with limited slip differentials. The vast majority of gear oils automatically come with it already mixed in. Not all but certainly most.
 
  • Like
Reactions: MountaineerTom
OP
MountaineerTom

MountaineerTom

LJ Enthusiast, Retired USAF Weapons Loader
Supporting Member
Ride of the Month Winner
Joined
Sep 25, 2018
Messages
4,308
Location
Sumter, SC
I was looking at an older bottle of Valvoline I have in other weights. They say for Limited Slip right in the bottle but don’t say for top off only on the back. I have a newer bottle if the same weight Valvoline that does NOT say for Limited Slip on the bottle but DOES say for top off only on the back. I guess Valvoline changed it up some over the years.

The 85w-140 I plan to use says for top off only so I’ll pick up some fri action modifier too.

Thanks for all the info.
 

pagrey

TJ Guru
Supporting Member
Joined
Apr 10, 2018
Messages
7,542
Location
Los Angeles, CA, USA
If it says okay for LSD then you don't need anything extra. If you don't have enough it will chatter and you can add the modifier. I wouldn't add anything unless it complains. I've never had a problem with mine in all the years I've hammered on it. At 140k+ it was still surprisingly effective on the street. When I got a real locker I noticed right away I could spin the inside tire on the street much easier with it fully open. It's one of those deals you don't know until you test it back to back with an open diff.
 

Blackjack

Evil Winch Doctor
Supporting Member
Joined
Dec 16, 2018
Messages
2,183
Location
Kenai
Great, thank you both.

That leads to my next question. I’ve seen lots of gear oils that say for limited slip but on the back of the bottles is may say something like Limited Slip for top off only. What exactly do they mean by that? What else are you supposed to fill it with if you doing an entire fluid change?

Use friction modifier anyway?

It means that the additive package in the oil will not harm the limited slip. You should always use a quality friction modifier (OE Ford, Chrysler or Spicer) with clutch type limited slips.
 
  • Like
Reactions: MountaineerTom

Jerry Bransford

TJ Guru Moderator
Staff Member
Supporting Member
Joined
Nov 9, 2015
Messages
24,316
Location
Fleming Island Florida
It means that the additive package in the oil will not harm the limited slip. You should always use a quality friction modifier (OE Ford, Chrysler or Spicer) with clutch type limited slips.
Which is already contained in 99% of all GL-5 gear lubes. It's hard to find one on the store shelves that does not have the additive package.