Well if there is a leak then I would suggest putting a piece of cardboard under your car at night when you park. If their is a leak, it will be on the cardboard when you come to your car in the moring. Now dont let oil change places rip you off. Dont buy the air filter and all that crap. The one thing I would spend the extra money on is the actual oil. Now if your car is newer then you can get buy with getting an oil change every 5000 miles. If it is over 70,000 miles I would get one every 3000 miles. Also I would have a semi tune-up twice a year. The main thing with a car is to get a good mechanic. I know dealerships are the most expensive, but they know what they are doing and do good work.