[jsvette]

Originally Posted by GreenC7Z-51

It's important on any new car to look it over during the break-in. I like to do longer trips for several reasons. Stop start city driving is harder on the engine than a long drive. Longer runs at higher speeds will reveal a leak quicker due to the air currents around the car. Drive the first 50-75 mi. Then stop and go over the car, look at the back for any oil, this is where it will show up first. If you see excess oil on the back of the car you need to look for a source. In my case all looked good for the first 200 miles, then at 400 while fueling I noticed a fine film on the rear panel. No source was evident at that point, but on the next stop at about 600 mi. I noticed more on the rear. I decided to get it put on a lift and find the problem.
The Coolers for Trans. & Dif. are behind the rear tires on both sides, the passenger side is the dif, and that's where we found the most. It turned out to be a fitting on the cooler, perhaps a pinched 0 ring, but they changed the entire fitting.

Great advice!