Although most drivers know that an oil change is part of a smart car maintenance routine, knowing when to have it done isn't as simple. Recent changes in cars and oil have changed some of the old rules. A bit of research and knowledge of the basic signs can help you keep your car running well.

Mileage and Time

The standard used to be that you changed your oil every 3,000 miles or three months, whichever came first. That rule no longer holds true because of the changes in engine technology and improvements in synthetic oil. How often you need an oil change depends on your car. A peek inside your owner's manual will give you the proper recommendation. The average is once per year or every 5,000 to 10,000 miles, with the high end being at 15,000 miles.

Take a Peek

Even with longer intervals between changes, you should still check your oil once a month. Regular oil checks allow you to catch potential problems early, so you can avoid a costly repair. The dipstick for checking the oil is beneath the hood. It's clearly marked and usually has a yellow handle. Always warm up the car to ensure an accurate reading.

The stick should show full or close to full unless you have a leak, so you are mainly checking for oil color.Very little oil is burned off by modern cars, so a major drop in oil levels is cause for concern. If the oil is dark and dirty, you need an oil and filter change. Oil in good condition can range from light yellow to reddish-brown in color.

Listen and Sniff For Trouble

A knocking noise is a sure sign of a problem. If you hear an engine knock, you need to get in for an oil change right away. At the very least, check and top off the oil. Your engine isn't receiving the lubrication it needs, which can cause it to seize. If the noise persists after an oil change, you will need to get it diagnosed and repaired quickly.

Even if you skip checking the oil, your car will give you other clues that it's time for a change. You may notice the odor of burning oil, especially when idling or accelerating. If you recently checked your oil or had an oil change, this smell is likely of no concern. Small spills or droplets of oil may have fallen on the engine and you are smelling these as they burn off.

Each time you have an oil change, make sure the oil filter is also replaced. Reputable shops include the filter as part of the oil change package.