1995 Pontiac Grand Prix mileage: 74,500. My engine is leaking oil. There is no puddle of oil under my car; therefore, it must be burning up somewhere. I have had the gaskets in the distributor shaft replaced by a reputable mechanic who thought that was the problem. But, I have only driven twelve hundred miles and have had to put two more quarts in already. In twenty five hundred miles, I've had to add four quarts of oil. Is my engine bad? Should I ditch the car?