Rear Differential Fluid

Been slowly but surely getting this truck squared away since I brought and I'm down to the last task: changing the rear diff fluid. I have the locking differential(which came in real handy on a recent drive through deep sand), what's the best fluid I can use. Should I use LSD additives(on the truck)?

 

75w90 for stock use, no LSD additives required.

You can also step up to an 85w140 weight Lucas if you want a little more protection

 

Isn't LSD additive used on 2005 - 2008 trucks with the mechanical LSD?

 

for the lsd yes

locker no

and whatever

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

75W-90 is the best bang for your buck IMO

 

I'm not 100% sure. I just read if you have the rear diff lock button it's LSD.

 

It's not an LSD. I'm 100% sure.

 

You only need the LSD additive for mechanical LSD which is 2005 to 2008 models as mentioned above ^
I used 80W90 with Posi-Trac additive and it works like a beauty. No more shudder when I put the foot down on a tight corner.
I personally don't see a benefit of using the synthetic (75W90). It's 3x the price and the conventional lasts two years anyways.

 

The rear diff lock and LSD are two different things. The rear diff locker is a locking differential, the LSD is a limited slip differential. TRD ORs come with the locking diff, TRD Sports from 2005 - 2008 come with the limited slip (and require LSD additive). 2009+ Sports do not have a real LSD, just a brake feature that mimics one.

You can use gear oil with LSD additive in the locking diff if you want...but it's not necessary. Won't hurt anything though.

 

Oh ok I just thought the trd offroad still had LSD in normal operation and locked differential when the locker is engaged.

 

I love it when the cheapest option is best. Is there really an advantage to heavier oil like 85-140?

 

I don't know if the newer TRD ORs might have the same 'pretend LSD' braking feature that the 09+ Sports have...it very well might. But because there isn't an actual limited slip in them, no LSD additive is needed. Can't have a mechanical LSD and a locker in the same diff, two completely separate devices for traction.

 

Ok but I was talking about the original poster looks like he drives an 05. Anyway good info. I didn't know they were completely different.

 

Nope standard open diff without clutch packs on the elocker diff (doesnt mater the model year)

Elocker diff doesnt care if you put LSD additive in it. I rock

$30 mobil 1 75w-90 synthetic gear lube - 1 quart (pack of 2)

mobil 1 75w-90 in my rear diff (that has LSD additive in it) without issue.

 

Oh gotcha, I thought we were talking about the other guy you quoted earlier. Yeah it does say he's an 05, but since he has a TRD OR he has a rear diff locker and therefore no LSD, so no additive required.

 

I think heavier oil is for warmer climate + heavy usage. The hotter your diff. gets, the thinner the oil becomes and the less protection it can provide.

 

This is why I asked about it. Learn something every day.

 

a lot of guys that offroad their trucks really hard will put heavier gear oil in the diffs for added protection against heat that builds up fast when you're wheeling. But if you live in a really cold climate it might not be a good idea, since that heavier oil is thicker

 

I drive off road a lot, but definitely not wheeling. I need to get home. 75-90w should work for my mixed terrain driving.

If the Walmart Supertech 75-90w at $6.95/qt is good, 3 qts and a $5 pump, about $25, well worth it.

I used to race cars and spent a lot of time in Baja. I prefer to prevent as many problems as possible instead of (off)roadside repair. Can't win if you don't finish.

 

You'll be perfectly fine with that. I run 75-90 in both of my diffs and wheel semi-frequently. This is also my DD.

 

yeah that's totally fine. Most people still run the 75w90, including myself and I do wheel pretty hard sometimes. I've thought about doing a heavier oil but only because my pinion seal has a small leak and I'm hoping it will slow it down lol.