What Lube Goes In My Buick Roadmaster Rear End?

What kind of lubricant does the 94 Buick Roadmaster Estate Wagon use in the non-slip differential?

It uses regular 80-90w gear oil in the rearend, but there is an additive for the limited-slip unit which you can get at any GM dealership.

I used a 90 weight but the clutches are sticking, I believe. Do you know what the additive is? P.S. I’m in Mexico near Guadalajara and there are dealers but the Buick’s are newer models.

The additive is for the clutches, it prevents unwanted sticking and noise from the differential assembly. I’m not sure of it’s exact chemicals, but you need the additive along with the oil for proper function. I’d recommend only using the GM additive. Any GM dealer worldwide can supply you with the additive, it’s just a small bottle, only a few ounces. The part number for the additive is 88900330. if you’re interested, we can ship you a bottle of the GM additive at a reasonable price plus shipping.