Rear diff service

[stilix]

Hey guys what fluid do you recommend for the rear differential thanks.

 

[Sasquatch]

I use royal purple 75w90 but any 75w90 will work.

 

[rich5368]

I use RP as well. Mobil makes good stuff too.

 

[chevy_man]

Napa stuff is re-branded valvoline or so I hear. Usually quite a bit cheaper.

Any brand name synthetic should do, and I only say synthetic because nobody ever changes it, and it should get you that extra .005% fuel mileage...

 

[zaathur]

i have castrol 75-90 full synthetic in mine just make sure its synthetic, if i change mine again i'm going with locus

 

[91RS]

Synthetic 75W-90 is REQUIRED. They come factory with synthetic, make sure you get one that comes with the limited slip additive (like RP or Amsoil) just in case.

 

[chevy_man]

Synthetic 75W-90 is REQUIRED. They come factory with synthetic, make sure you get one that comes with the limited slip additive (like RP or Amsoil) just in case.

You DO NOT need limited slip additive unless you have added one with clutches yourself. The factory locker/limited slip is all hard parts with no clutches (and famous for self destructing).

 

[91RS]

You DO NOT need limited slip additive unless you have added one with clutches yourself. The factory locker/limited slip is all hard parts with no clutches (and famous for self destructing).

The G80 locker does have clutches and the GM fluid has the additive in it.

 

[chevy_man]

The G80 locker does have clutches and the GM fluid has the additive in it.

The 10 bolt G80 does not have clutches, it has a spring loaded arm that flips over with around a 20% difference in axle shaft speeds. The arm flipping over and catching is what normally breaks them. Here's a pic so you can see for yourself:



Here's an old pic I have of an exploded one:



And here's a clutch type LSD:



And no, the GM fluid does not have additive. It's just super expensive because it says GM.

 

[91RS]

Looks like clutches to me: