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View Full Version : Anyone use Castrol Syntec Gear Oil?



fbody_mike
06-10-2011, 09:03 AM
Anybody use Castrol SYNTEC gear oil in their limited slip diffs? Catrol claims it contains the friction modifier for the limited slip clutches. Granted I only have 15 miles (first break in) on a newly rebuilt rear end but it feels a little "catch and go" on very slow turns. No noise, and at higher speeds it feels fine.

Should I give it a little longer? Do some figure-8s, or just pour in some GM limited slip additive?

JEFFTATE
06-22-2011, 05:52 PM
It won't hurt to add a bottle of limited slip additive on top of the synthetic lube . Try it and see .

Does your limited slip unit have the earlier fiber clutches or the later carbon clutches ??
I've heard not to use synthetic with the early style clutches.

Either way , try the LS additive first .

CarlC
06-22-2011, 09:23 PM
Does GM still carry the additive?

chicane67
06-23-2011, 06:25 PM
It normally takes a little while for the fluid to 'work' into the clutch pack. At 15 miles... that isn't enough time on the unit for it to give you a real idea if it will require more fric mod or not.

However, I would only add enough to make your noise subside. Meaning... I would only add about 2 oz at a time.

I myself like the Ford Fric mod better than the GM stuff (I know, sacrilege)... but, it is available in a 4oz bottle.

JEFFTATE
06-24-2011, 12:20 PM
Does GM still carry the additive?

Yep !

GM Part # 1052358

CarlC
06-26-2011, 02:45 PM
Hey Tom, what was that Schaeffer and/or Torco diff lube you liked?

JEFFTATE
06-28-2011, 06:29 AM
Torco RGO .

fbody_mike
06-28-2011, 06:56 AM
All the low speed catch and go on the turns went away after about 75 miles. Feels great now, did not have to add any additive.

John Wright
06-28-2011, 07:00 AM
I myself like the Ford Fric mod better than the GM stuff (I know, sacrilege)... but, it is available in a 4oz bottle.
Yup, I use that too.

BTW, just a little word of caution......don't go out at lunchtime and purchase your fric-mod and leave it inside your vehicle until you get off work during the Summer months. (unless you like that sort of smell permeating from your vehicle for months to come)