Rear differential leaking
 

1998 ML320, 107K mi. I noticed a small leak under the rear diff a while back. A closer inspection today revealed a leak out the driveshaft seal that's getting quite serious. I would not hesitate to do this repair on other vehicles I've owned in the past, but the ML is the first car I've owned without a proper shop manual. Anything unusual about this job on this car? Any special tools? Is this a common problem?

Will Mobil 1 or Red Line 75W90 gear lube work OK? Manual calls for 85W90; I assume that's dino oil? I plan on 300,000 miles minimum on this car, would prefer to use synthetic lubes. I really need to fix this before my wife drives to Texas next week (1,200 miles each way).

Thanks for your input.

Lenny

Rear differential leak @ input shaft
 

Dealer says 5 hours for this repair. This seems high, is there a lot more to the job than meets the eye? Are the MB seal drivers absolutely necessary, or can they be installed by careful application of a drift punch?

Next closest dealer (in Kalamazoo) looked in his book and said 1.1 hours for changing the seal, it's really no big deal, but his backlog was a week. I decided to go for it. All went fairly well (had to dig around to find a 16 mm socket to take the driveshaft off; what an odd size). When I do the front I will try to fashion some sort of seal driver--the seal fits quite tightly and it's a struggle to get the new one in straight without a proper driver. Still the leak was eliminated and my wife just arrived in Texas, just missing our ice storm.

For whatever it's worth, I would say the parts and service phones in Kalamazoo are staffed by more knowledgable people than those in Grand Rapids.

Lenny