As a general rule, you should check your motor oil every 1,000 miles. This 1,000-mile milestone will also give you the opportunity to check for leaks. If you notice you are going through more oil than you generally do or more than one quart every 1,000 miles, it's time to call your Servicing Dealer for an appointment and diagnosis. Remember to change your motor oil every 3,000 miles as a general rule. If you commute more than 200 miles per day, you can push that interval up to every 5,000 miles.
Shorter trips require more frequent changes.
To check the automatic transmission fluid level, your car also needs to be on level ground. Set your parking brake and start your engine. Keep the engine idling in park, and fine your transmission fluid dipstick. If you're not sure where it is, consult your owner's manual. Pull the stick out and wipe any fluid residue from the end.