which gear oil for limited slip

[goodoleboy]

I have 1989 chevy truck with 4x4 and limited slip/or posi traction rear end unsure.

Which 80w90 fluid do I use. Some bottles say for for top off only not refill.
I say castol HYpoid C is that made for limited slip?
I like to buy local if possible.

 

[dustyjoe1]

Mobil 1 will work without the additive. According to the tech guys at 800 ask mobil you can add it or not, its up to you but it will work without it. Seems to do fine in a ford expedition 3.73(limited slip I understand)

 

[TheFuror]

quote:

---

Originally posted by goodoleboy:
I have 1989 chevy truck with 4x4 and limited slip/or posi traction rear end unsure.

Which 80w90 fluid do I use. Some bottles say for for top off only not refill.
I say castol HYpoid C is that made for limited slip?
I like to buy local if possible.

---

I would find out what actual GM part number you need, and then get the GM gear oil from http://www.gmpartsdirect.com. This way there is no confusion and you will save a bundle over what the dealer would charge.

Bob W.

 

[Butch 02 Sierra Denali]

Aren't all oils labeled GL5 suitable for use in limited slip?

 

[TheFuror]

quote:

---

Originally posted by Butch 02 Sierra Denali:
Aren't all oils labeled GL5 suitable for use in limited slip?

---

check out this post, from http://www.swedishbricks.net/700900FAQ/Driveline1.html

"[Note from Michael Asmussen, Torque Control Products Division of Eaton Corp.] We recommend the following lubrications for our locking differentials:
1)Texaco 2276; Synthetic 75 W90; Gm Part # 9986115
2)Texaco 9622; Mineral based 80W90; GM Part # 9985290
3)Texaco 2080; Synthetic 75W140 (heavy duty applications); GM part # 9985991
Note - All of the above lubes are preblended with friction modifier. No additional modifiers are necessary or recommended. As far as other lubes are concerned, any standard GL 5 lube will work, but the units perform optimally with the three listed above."

Bob W.

 

[KJA426]

A lot of GL-5 bottles say no additive is necessary. My Auburn needs GM or Ford additive because it sounds and works poorly with GL-5 80w90 alone.

 

[heyjay]

Are you sure it's a Limited Slip? I always thought GM/Chevy trucks could be ordered with the RPO G80 or GovLok.

That design uses clutch plates but also a mechanical flyweight that latches when a wheel starts to slip, thus forcing the clutch plates together.

A governor attached to the flyweight pushes the weight away from the pawl over a certain speed, usually 25 MPH. This prevents engagement at highway speeds, which could cause the rear end to slide out for example on ice.

I bought new a 1985 Ford F-350 2WD with 6.9 diesel and four speed. I put a Detroit Locker in the rear Dana and had a VERY fun incident one snowy winter night when the truck was empty: the rear end spun out on a hill and I just about s*** myself.

I used to have a 2000 GMC Sierra with the G80 rear end. I had good luck with Mobil 1 Gear Oil 75W-90 and 75W-140, with a tube of CRC PosiTrak limited slip additive: the locker worked very well.

 

[tblazed]

G80 in a GM car will be limited slip i.e., the clutches are always engaged so when you go around corners etc. the clutches have to "give". That's why the limited slip additive is needed- so that happens smoothly and it won't chatter or make noise turning corners. Some newer GM cars have the Gleasen-Torsen type limited slip dif that has no clutch pack inside but use helical gears instead.

G80 in a GM truck will be a locking dif. Clutch pack is disengaged unless wheel spin below 20 mph is happening, then the centrifugal weight mechanism will engage or lock the axles together through the clutch mechanism.

I just changed the factory dif oil in my 2002 Trailblazer/G80 locker with Royal Purple 75W-90 that meets the needs of all including limited slip.

 

[Ken2]

quote:

---

Originally posted by Butch 02 Sierra Denali:
Aren't all oils labeled GL5 suitable for use in limited slip?

---

No. GL-5 just tells us that the gear oil is suitable for hypoid gears.
http://auto.howstuffworks.com/gear4.htm

Most differential gear oils do contain the limited slip additive. Some GM differentials do require a special gear oil. Check the "Chek-Chart" in an auto parts store.


Ken

 

[metroplex]

Redline 75W-90 works great for many people with clutch posis that call for friction modifier + 80W-90.

Some synthetic gear oils do NOT contain FM additive (M1 75W-90) and you'll end up trying to fill it to the right amount.

My advice is to use the synthetic gear oils formulated for use with limited slip differentials. It takes the guess work out of adding the FM additive.

 

[Fred Bear]

In my work truck,a 99 F-150 with limited slip. It calls for 75W-140 SYN ONLY. I was going to use the Mobil 1 and add the FM but I saw the Royal Purple 75-140 for 4 dollars a QT cheaper (9 vs 13) and I didnt have to buy the FM.
It seems to be working fine. No clatter when turning, ect..

 

[kevm14]

What fluid would maximize the friction in my cone-clutch Auburn posi (95 Camaro)? Right now I have a fill of whatever jiffy lube put in, which I think is valvoline 80W-90. Posi action is still there, but kinda weak. I wanted to get all I can out of it before the first snow...

 

[heyjay]

It sounds like your cone clutches are worn, and there is nothing that will "cure" that except a rebuild.

Auborn warns against using any synthetic: 80W-90 mineral with FM

 

[Tremo]

I have an 88 Camaro with a cone type posi. I have been running a 50/50 mix of Royal Purple and Redline synthetics, both 75W-90, and both with built-in LS additives. I didn't add any additional LS FM to the thing. Runs fine, no chatter. I'm sold on synthetics, I run all synthetic fluids in the car.


The above poster is correct though, if your cones are worn, it's rebuild time, nothing short of that will fix it.