Differential questions

[BlindBaby]

A have a couple of questions about my two trucks.

Truck No. 1: 2009 Chevrolet Silverado 1500 4x4. The owners manual doesn't state the truck has a limited slip differential nor does state the truck may be equipped with one. The truck requires a 75W-90 gear oil, that being said, will it harm the differential if I run the proper weight gear lube that contains the friction modifier required by LS differentials?

Truck No. 2: 2007 Dodge Ram 1500 4x4. The owners manual states the truck may be equipped with a limited slip differential. How do I determine if the differential is a conventional axle or LS differential?

This truck requires a 75w-140 weight gear oil. Why would this truck require this weight oil when the 2500 and 3500 series Dodge trucks require 75w-90 gear oil?

 

[MrkofXcellence]

The GM pickups of late (at least 2004 onward) do not require friction modifier to be added to the 75w90 fluid, even if equipped with the limited slip rear end. So in that department you're covered. Just make sure you use synthetic 75w90 oil (though I think that's all there is). If for informational purposes you want to see if you have a locking rear end in your pickup just check the sticker inside the glovebox. If you see G80 listed then your truck has the locking rear end. No G80 no locking rear end.

 

[clinebarger]

GM trucks have used the Eaton Gov-Loc since the early 80's, The Eaton Gov-loc does not require LS additive.

 

[Colt45ws]

The Dodge might require the heavier oil because the smaller differential has less fluid in it and the gears and bearings are under more load for a given contact area than the bigger axles used in the 3/4 and 1 ton trucks.
I would just buy a 75W140 that has a Friction modifier added. It'll work fine in either open or LS diff. I used Amsoil Severe Gear 75W140 in my Step-moms old '04 Ram that had a Limited slip. No noise going around corners.
As far as telling if it has a limited slip or not, you can jack up both sides of the rear axle and see if the tires will spin. If they are locked to the driveshaft, then it has a LS.
Ooooorrr, they way I personally would check is take it out on a out of the way street and do a quick brake stand, then go back and see if it left two skid marks.

 

[barkingspider]

In my silverado and escalade, I have used ST and Delo 75w90. Neither have limited slip additive in it and it works perfect. I would use a fluid without the LS. Sorry I never messed with a Ram truck

 

[Kuato]

Originally Posted By: BlindBaby
A have a couple of questions about my two trucks.

Truck No. 1: 2009 Chevrolet Silverado 1500 4x4. The owners manual doesn't state the truck has a limited slip differential nor does state the truck may be equipped with one. The truck requires a 75W-90 gear oil, that being said, will it harm the differential if I run the proper weight gear lube that contains the friction modifier required by LS differentials?

Truck No. 2: 2007 Dodge Ram 1500 4x4. The owners manual states the truck may be equipped with a limited slip differential. How do I determine if the differential is a conventional axle or LS differential?

This truck requires a 75w-140 weight gear oil. Why would this truck require this weight oil when the 2500 and 3500 series Dodge trucks require 75w-90 gear oil?


1: No.

2: Jack up the rear end. Put transmission in neutral. Rotate one tire.
If the other tire goes same direction = limited slip.
If the other tire goes the opposite direction = open differential.

 

[Ducman]

Originally Posted By: Kuato
Originally Posted By: BlindBaby
A have a couple of questions about my two trucks.

Truck No. 1: 2009 Chevrolet Silverado 1500 4x4. The owners manual doesn't state the truck has a limited slip differential nor does state the truck may be equipped with one. The truck requires a 75W-90 gear oil, that being said, will it harm the differential if I run the proper weight gear lube that contains the friction modifier required by LS differentials?

Truck No. 2: 2007 Dodge Ram 1500 4x4. The owners manual states the truck may be equipped with a limited slip differential. How do I determine if the differential is a conventional axle or LS differential?

This truck requires a 75w-140 weight gear oil. Why would this truck require this weight oil when the 2500 and 3500 series Dodge trucks require 75w-90 gear oil?


1: No.

2: Jack up the rear end. Put transmission in neutral. Rotate one tire.
If the other tire goes same direction = limited slip.
If the other tire goes the opposite direction = open differential.


Or you could simply look at the filler hole bung at the back of the housing.
A LSD will usually have a rectangular tag under it stating the diff is "spin resistant"/"limited slip".

The thicker oil is often a requirement for an LSD center and or a design which has a high pinion angle offset.

 

[DuckRyder]

Dodge (and Jeep) frequently have a tag around the axle tube near the backing plate...

 

[zeng]

Originally Posted By: BlindBaby
Truck No. 2: 2007 Dodge Ram 1500 4x4.This truck requires a 75w-140 weight gear oil. Why would this truck require this weight oil when the 2500 and 3500 series Dodge trucks require 75w-90 gear oil?

75W140 is for OTR prolonged usage and 75W90 is probably for feed to junkyard,I suppose.

 

[4wd]

Sometimes engineering looks at heat - assumption being the 75w-90 cools better - and possibly better in conjunction with the finned aluminum covers starting to gain in use from factory and aftermarket.
My G80 is filled with Mobil Delvac Synthetic 75w-90 ... This stuff goes serious miles/hours in heavy trucks/equipment ...
One of the BITOG Gurus recently explained while it has FM - it is not the same chemistry as normal LSD application ...
(Wear/temp?)
My diff is smooth & quiet - but "scratches" dead even on tires ...

 

[HerrStig]

Originally Posted By: Kuato
Originally Posted By: BlindBaby
A have a couple of questions about my two trucks.

Truck No. 1: 2009 Chevrolet Silverado 1500 4x4. The owners manual doesn't state the truck has a limited slip differential nor does state the truck may be equipped with one. The truck requires a 75W-90 gear oil, that being said, will it harm the differential if I run the proper weight gear lube that contains the friction modifier required by LS differentials?

Truck No. 2: 2007 Dodge Ram 1500 4x4. The owners manual states the truck may be equipped with a limited slip differential. How do I determine if the differential is a conventional axle or LS differential?

This truck requires a 75w-140 weight gear oil. Why would this truck require this weight oil when the 2500 and 3500 series Dodge trucks require 75w-90 gear oil?


1: No.

2: Jack up the rear end. Put transmission in neutral. Rotate one tire.
If the other tire goes same direction = limited slip.
If the other tire goes the opposite direction = open differential.
This & .

 

[Chris142]

Put a tire in the dirt and the other on street. Gas it. If the one on the street squeaks it's got a posi