Limited slip or not?

[NavyVet88]

Just wondering how I can go about determining whether or not my truck has limited slip or not. I need to change the differential fluid and I'm not sure if I have to add the limited slip additive to the pumpkin or not.

All I can find in the manual is that it states it needs 80w-90

 

[Ramblejam]

There are a few ways. What's the truck in question?

 

[bdcardinal]

What type of truck, if it is a Ford look on the differential tag. Where it gives the ratio there will be a L, like 3L73 instead of 3 73.

 

[NavyVet88]

1994 Chevy C1500 5.7L 2WD

 

[Ramblejam]

Look in the glove box and you'll find a "Service Parts Identification" tag (RPO codes).

Search for G80.

 

[bluestream]

Just use Red line fluid as it has the FM in it already and fine for NS differentials

 

[Cujet]

A conventional limited slip (not a torsen or other exotic) will not allow you to hand-rotate one tire if in neutral. With that tire in the air and all other tires on the ground.

If both tires are in the air, and it's in park/in gear (if manual) rotate one tire by hand, if the other rotates the opposite direction, it's an open differential.

 

[NavyVet88]

Originally Posted By: Ramblejam
Look in the glove box and you'll find a "Service Parts Identification" tag (RPO codes).

Search for G80.



Negative GU6 is the only G code on the tag

 

[Ramblejam]

Then you have a 3.42 axle without limited slip.

 

[NavyVet88]

Originally Posted By: Ramblejam
Then you have a 3.42 axle without limited slip.


10-4 thanks boss

 

[splinter]

Originally Posted By: Ramblejam
...Search for G80.

Which, incidentally, typically requires no special 'limited slip' gear lubricants and/or friction modifiers owing to its mechanical function(s).

https://www.youtube.com/watch?v=KbMZ9vcYVSg

 

[barkingspider]

Any 75w90 would be good for it

 

[Doog]

Valvoline 80w90 will work fine. If you get a synthetic like Amsoil or Redline you can go twice the OCI.

 

[mongo161]

You can also get full synthetic Pennzoil or Mobil 1, 75w90 by the case of 12, on Amazon. A lot less money than the auto parts stores or WM.

 

[NavyVet88]

I had the valvoline 80w-90 In mind or maybe the super tech 80w-90 because it's 4.47 at Walmart. What kind of interval do you think I should do? I was thinking 15k

 

[mongo161]

With the synthetic gear oil, I go 40K between changes. However, I like to add 1 quart of Mobil 1, 75w140 to the rear differential when I change the fluid. 2.25 quarts of Mobil 1 75w90 and 1 quart of Mobil 1, 75w140 since I sometimes carry heavy loads or do some moderate towing.

The mix holds up well for 40K.

 

[NavyVet88]

This truck doesn't do any pulling it may carry a riding mower in the back or some stuff from our storage unit to the house and that's about it

 

[gathermewool]

Originally Posted By: Cujet
A conventional limited slip (not a torsen or other exotic) will not allow you to hand-rotate one tire if in neutral. With that tire in the air and all other tires on the ground.

If both tires are in the air, and it's in park/in gear (if manual) rotate one tire by hand, if the other rotates the opposite direction, it's an open differential.


One wheel of a torsen (or gear-type) LSD will rotate in the opposite direction, with both in the air. It effectively becomes an open differential with zero grip at both sides.

 

[donnyj08]

You can use a 75w90 for a few dollars more and run it out to 30-50K miles if your only doing light duty usage.

 

[HerrStig]

Position the vehicle with one rear wheel in dirt or sand and the other on hard pavement. nail it. If you barely move while spinning the tire in the soft stuff it ain't no limited slip.