I was looking at my service sheet, and saw just the differential, a vent kit and gear oil..... I did not see limited slip additive. I wonder if the dealer was out of it, or if this is the new procedure? The mechanic said it was synthetic gear oil. Would this have an effect on the differentials break-in?
On another note... I can't believe your on number four.. I thought the 2006+ diffs. were new an improved. I can say one thing about the replacement i got.. The driveshaft L/R slop is alot less compared to my original 04 differential.