Just got my Solstice out of the dealer. My car has only 6000 miles. I noticed a drip off the rear of the diff. After doing lots of reading, I thought it was either the pinion seals or the vent. It turned out to be the vent. They have a TSB on fixing this BUT IT DOESNT WORK. The mechanic took of the vent on top of the diff housing and tried to add an extension hose routing this up and higher in the vehicle. The problem is two-fold. One, there isn't enough clearance to route a vent hose without bending and kinking it off. Two, there is not enough of a nipple on the vent housing to clamp the hose to. I drove home after this fix and had diff oil all over my garage.
The car now has a brand new diff. They have apparently fixed the vent leak by re-design and placing a baffle in the housing below the vent to keep the oil from splashing out. This diff is common to other vehicles as well including some cadillac models.
