2001 Grand Prix GTP - Coolant and oil loss

Don't know if this helps, but here's a suggestion. I own a 2003 Buick Regal, also a 3800, with a lot of miles. I was noticing an oil loss as well but couldn't find a trace of a leak, nor was it burning or in the coolant. Then, it came time for new engine and transmission mounts. When I removed the engine mount on the passenger side, there was a bout 2 cups of oil collected in the engine mount cradle. As it turns out, the leak was coming from the front of the oil pan, and leaking into the cradle. The cradle was collecting it, therefore no oil spots on the ground. And it's pretty much a straight drop into the cradle, so any dies would not even see a leak. All you have to do is remove your right front wheel, put your hand into the cradle that holds the engine mount and see if there is pooled oil. If so, there's your oil leak! As for the coolant, check the plastic elbows that go from the alternator bracket into the engine block on the right side of the car, just below the intake. These are very prone to leak, and their location makes it hard to detect.

I replaced the coolant elbows last year with Dorman metal ones. All visual areas are bone dry. As far as the oil goes, I will have to check the cradle when I get a chance..