rkink

I'm getting ready to change the diff fluid shortly and called up my local dealer to see if he had the GM # 12378261 synthetic fluid as indicated in the owners manual. He says this has been replaced by # 89021677, also a synthetic. When I asked about the limited slip additive # 1052538, he says this is not required with the 89021677. I think he is wrong. Can someone verify?

itzza427

It may already be in there. I used Royal Purple Max Gear,,and it has the limited slip additive already in it!!

c5blkvetteguy

Gene culley (gmpartshouse) hooked me up with the new stuff that is being used in the c6's. The friction modifier is in it, and the price was right!

robsc501

Hi There:
Did a google search gm 12378261 was replaced by 89021677 which as a earlier poster stated contains the modifier.
robsc501

I Owned U

So if I go buy 2 quarts of the new fluid (89021677), I dont need to buy the LSD additive (1052358) from GM as well?

Glennm27

Many new fluids these days do NOT require the additive. He's probably correct.

clayton1

rkink

So is the 89021677 the new Dexron fluid the dealerships are recommending for the C6's? If so, it is my understanding that the C6 fluid should not be used in C5's?