What Fluid to use for Front/Rear Diff? LS Additives?

I'm planning on doing fluid changes in my new-to-me (bought in December) 2013 base, 4x4 MT. I'd like to change the front and rear diff, transfer case, and transmission fluids. Truck has just over 70k miles and I'm not sure if these fluids have ever been changed.

Based on research here I was planning on using redline MT-90 for the manual transmission and transfer case.

It seems like most folks on here go with

$30 Mobil 1 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

Mobil 1 75W-90 fluid for the diffs. My question is do I need LSD additive? From what I've read on here trucks newer than 2008 don't have a LSD, but when I looked up my spec sheet with my VIN number I got this:

5-Speed Manual Transmission 4WDemand: Part-Time 4x4 Sys w/ 2-speed Electronically Controlled Transfer Case Automatic Limited-Slip Differential

What type of gear oil should I be using for my front and rear differentials? Do I need something that has LS additives in it?

I've changed engine oil plenty of times, but this will be my first time changing differential, transmission, and transfer case oil, so I want to make sure I get it right. I'd appreciate any advice or input. Thanks!

 

I just solved a problem that mine encountered by using Car Quest full synthetic and a friction modifier additive. I went back to Valvoline 80W-90 dino and the friction modifier, that stopped the chatter.

My differential is mechanical. The electronic controlled ones may be different but I would sort of doubt that.

 

According to pp 458-460 of your Owner's Manual, Front & Rear Diffs require "75W-85 GL-5 or equivalent," MT & Transfer Case require "Gear oil API GL-4 or GL-5 SAE 75W-90." LSD additive is not required, as our "AUTO LSD" relies on the electronic Vehicle Stability Control (VSC), rather than mechanical clutches.

For convenience, I run Amsoil Severe Gear 75W-90 in all of them. (It's recommended for differentials, manual transmissions and other gear applications requiring GL-5; and can be used in axles where GL-4 is recommended.)

 

@Shellshock

 

Thanks for the feedback. Do these trucks come stock with dino or synthetic gear oil in them?

Also what do you mean when you say "chatter"? I notice sometimes when going over washboard type bumps (welcome to RI) that there's some chatter that seems to come from underneath, but sounds almost more like its coming from the transmission than the differential... seems to go away if I put it in neutral...

 

NO additive because your differentials are not mechanical limited slip. Only the 2005-2008 Sport had a LSD in the rear.
However, synthetic gear oil (Mobil 1 75-90, for example) do not need additives even if you had LSD clutches in the diff.

 

Redline MT-90 works great in the 5 spd manual, I use it in mine. Auto LSD uses the brakes electronically to control wheel spin, and is not a clutch plate type limited slip.

Some users, and many manufacturers claim synthetic gear oil doesn't need the LSD additive. However, that has never worked for me in any vehicle with clutch plate type limited slip. I tried Mobil-1

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 in a 1998 Dodge, and a 2003 Tundra, and both chattered terribly, and I had to buy LSD additive, and put it in the rear diff after I did the fluid change to stop it. That's been my experience, but yours may vary.

 

I looked at my manual for my 2010 and the transfer case is the only box that calls for LS gear oil. I just changed all of the fluid in the diffs an x-fer case with mobile 1

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90. Only my rear differential is very dirty my transfer case was pretty clean and so was my front dif since I don’t use my four-wheel-drive that often

 

Thanks for the feedback all. Sounds like I'm going to go with the redline MT-90 for the transmission and a synthetic (mobil, amsoil, or valvoline) 75w90 for the diffs and transfer case. Hopefully all goes well!

 

Funny, but both times I changed the three (Front diff, Rear diff, Transfer case), only the rear diff was darkened and looked tired. I do use 4WD a bit but not daily, and the front diff and transfer case were clean, after 30-40 K.

 

Does anyone know if using a gear oil which comes with LSD additive would be harmful to a differential that is not limited slip?

 

I didn’t hurt mine…….
Been in there for 40k miles now.

 

Unless things have changed use only GL4 gear-oil in the manual transmission. This does not mean that a container that says: "GL5"/(GL4 compatible) is acceptable in the 2nd-Gen stick transmission. GL5 has a higher sulfur content and will wear out the synchros in short order.

 

It’s been 4 years since that post.
I bet he isn’t worried about it now.

(We all do it. Even I get pulled in to an “old” post)

 

Oops! lol. "Uncle Leo syndrome" I only noticed it after I already entered it all in and figured what the heck: it's good info to post once in a while.

 

True. Good post for people in the future that may come across this thread.