Additives like that rob too many people.

Change your oil and air filter every 3,000 miles (or sooner than needed).

Most manufacturer's recommend that you get a tune up every 50,000 miles, but if you race your car or drive it excessively hard on a day to day basis, you'll be needing to do a tune up more often.

If you don't know what all a basic tune up consists of, it's changing your air filter, changing or cleaning your spark plugs, replacing your distributor cap and rotor. If you want to ensure the best amount of protection, and proper engine performance, change your spark plug wires, PCV Valve, and O2 sensor.

It's worth it, and you'll sleep better at night.