BruceBufferTA

iTrader: (1)

So I recently had GM 4.10 put in my 2002 ws6. The shop that did the swap for me used Valvoline 80/90 lubricant. After looking in my owners manual, I see that it suggests I use a SAE 75W-90 Synthetic axle lubricant since it's a limited-slip differential. Am I going to run into trouble or have problem since they didn't use synthetic? I was also about to change lubricant after my 500 miles break in period so I'm curious if I should stick with the 80/90 or go over to a SAE 75W-90 synthetic and add the 4 ounces of limited-slip axle lube additive it suggest I use during a complete drain and refill.

Thanks

thunderstruck507

iTrader: (18)

as long as they added the limited slip additive it shouldn't matter, if you're changing it soon anyway why worry?

I use the valvoline synthetic and the small bottle of additive too

BruceBufferTA

iTrader: (1)

So that's it? Nobody else can give any feedback on weather or not running the conventinal lube 80/90 may have hurt anything and if I should switch to the synthetic when I change fluids this week?

udienow

iTrader: (18)

I know this may be a myth, but arnt u supposed to run conventional for the break in period? I am fairly sure u can switch to synthetic after the break in, but I am no expert.

MYSTIC-1SC

iTrader: (14)

as long as the limited slip additive was used dnt worry bout it.

vanveldhuizenc

I know alot of guys run conventional all the time but most do run it during the break in. I really don't think it matters that terrible much as long as you've got the additve in and its some kind of gear oil I put syn. 75w90 when i put my 4.10's in but i have torsen diff so I didn't need the additive in my car. As long as it was set up correctly and you put 4 oz of additive in and fill the rest with gear oil you're rear end should last you a good long time (as long as you don't over power it ) the only benifit of syn is that it doesn't succome to thermal breakdown as fast so fluid changes are few and far in between.

skanknova

iTrader: (3)

4.10's in the 7.5 10 bolt ? thats where your screwed! enjoy the few weeks while you can!

dlross

iTrader: (3)

i only use conv. oil in mine that is what moser wants no syn. but thats a 9inch not the 10bolt

TooLateVTEC

iTrader: (2)

I wouldnt worry about it if you plan on changing it soon anyway.

But when you change it, it should be synthetic and I think the Royal Purple stuff doesnt even need the small bottle of additive for the GM stuff.

Mumbles

iTrader: (5)

This is correct.

I swapped over to Royal Purple 75W-90 a couple years ago. I still have the factory 3.42 gears and I'm sure I didn't use an additive when refilling with the Royal Purple.

jimbo98z

iTrader: (3)

That has more to do with the actual differential. I'm assuming you've got a TrueTrac?