this really stinks. months ago dealer was working on my axle and they had to drain the differential fluid. i told them that i had posi and used special gear lube. they said that they put in all synthetic. well my posi made noise when i went around corners and pulled into parking spots. they used 75/90, i think. then they tried putting a limited slip additive. i was quiet again for a few days. i told them i used vavoline 85/140 and never had a problem. they ended up putting 75/140 and it was fine again for a few weeks. any suggestions? i don't feel like taking it back to the dealer since they screwed it up 4 times in a row now.

 

Change it out 1 more time and use the early ford additive

 

i never heard of this ford additive. where can you buy it? i was thinking of changing the fluid myself.

 

The ford dealer,its better and cheaper than the GM additive.

 

The proper combo for the Eaton LSD is regular dino 80/90 (no synthetic) plus GM limited slip additive. When the shop installed the Eaton in my Avalanche, the head guy said he was going to put in two packets (or whatever they are) of the additive instead of just one. All this shop does is differentials, and they built them for race cars and Baja race vehicles, so they definitely know what they're doing.

 

dino + ford additive recommended by randys ring and pinion

 

The GM additive is in a 4 ounce bottle. 2 bottles is not needed but should'nt hurt. The vette's use the synthetic lube with the additive. Put it in and go drive it, get in a parking lot and do some circles in both directions and some figure eights. This will force the clutches to slip. They make noise when they stick together. Once you break them loose, it should be fine.

 

I just installed a new eaton with gears. The eaton box said only to use 80/90 regular gear oil and limited slip additive. I never take my truck to the dealer. Something always ends up wrong after.