Rear End Fluid Changes:Next Question

[bigmack]

Definately interested in any info on the volume of GM limited slip additive that needs to be added.

 

I have heard info that you need all to 1/2 of the 4 oz bottle you buy from GM. That info came from the same dealer.

 

Also read on this site that some run without. I know the additive is a friction modifier used to prevent clutch shudder and that too much will tend to "slime" up the clutch packs and reduce lock-up.

 

Does anyone know "definativley""how much is required

 

Thanks.

[Bish]

Depends on your truck.  What year/make/model?

 

The factory locker (G80) does NOT use additive.  Just synthetic gear oil.  I run Mobil 1 as opposed to the $30/qt GM sh$t.

[Black02Silverado]

Depends on your truck.  What year/make/model?

 

The factory locker (G80) does NOT use additive.  Just synthetic gear oil.  I run Mobil 1 as opposed to the $30/qt GM sh$t.

Stated above you don't need it if you have the G80. If you have a posi like an Eaton with clutch packs then you just put in the whole four once bottle. I always have till I started running Amsoil's Series 2000 synthetic fluid. It already has the additive in it so there is no need to put more in. I rebuilt my 12 bolt in the 65 Impala and put a new Eaton posi with the new carbon clutches. It works like a charm and I used the Amsoil right from the start. No problems at all and it hooks up perfect. Can smoke both tires with ease.  Not sure if Royal Purple or Redline have the additive already in their fluid or not. You would have to call them up and find out.

 

Amsoil's Series 2000 75w-90 runs $9.20 a qt. You can get if off my web site or e mail me with any other questions.

 

:thumb:

[SilveradoWV]

I think a few others already have the additive also, but cant think of the brands! :thumb:

[rtbrick]

I just changed my fluid. Directions on the bottle from GM state to add the entire bottle.

[bigmack]

I've been adding the full bottle as per the instructions but wanted to clear up contradictions. It was the GM dealer shop foreman who told me the shop only adds 1/2 bottle. May be economics (twice as many trucks treated) but I'm sure there are alot of customers out there who have had their vehicles serviced "not to spec".

 

I change the gear oil at the end of each summer season as I tow a boat and tend to dump the rear end into the water on a semi regular basis.

 

The oil change is with 80W90 "dino" oil as I only see about 10K miles between changes and don't see value in the synthetics therefore I need the additive.

 

Thanks for the info.

 

G

[Dihappy]

Depends on your truck.  What year/make/model?

 

The factory locker (G80) does NOT use additive.  Just synthetic gear oil.  I run Mobil 1 as opposed to the $30/qt GM sh$t.

Stated above you don't need it if you have the G80. If you have a posi like an Eaton with clutch packs then you just put in the whole four once bottle. I always have till I started running Amsoil's Series 2000 synthetic fluid. It already has the additive in it so there is no need to put more in. I rebuilt my 12 bolt in the 65 Impala and put a new Eaton posi with the new carbon clutches. It works like a charm and I used the Amsoil right from the start. No problems at all and it hooks up perfect. Can smoke both tires with ease.  Not sure if Royal Purple or Redline have the additive already in their fluid or not. You would have to call them up and find out.

 

Amsoil's Series 2000 75w-90 runs $9.20 a qt. You can get if off my web site or e mail me with any other questions.

 

:thumb:

I dont know about the Eaton, but Auburn does NOT recommend synthetic.

 

Just thought id point that out.

[cyrylyn]

does anyone have the part # for this friction modifier stuff? There's nothing in the service manual about adding anything to the synthetic gear oil for the rear axle on my truck.

[Tweeter400]

From the factory, does the 1/2 ton G80 have synthetic fluid in the difs??

From what I am reading here, if you use synthetic you don't need additive, if you use "dino" you do?? Is this correct?

 

Thanks!

 

[Bish]

Mine came with GM synthetic in the rear ($27/bottle). I have been running Mobil 1 front and rear with NO additive for 90k so far (change every 25K).

 

The additive is NOT required on the G80. Since it is a locker, there is no friction material, therefore no need for additive.