Open your owner's manual (or go online if you've lost it) to find out what the manufacturer recommends. Start with the manufacturer's recommended mileage interval or time interval and recommendations for weight, also called viscosity.
If you've read the manufacturer's recommendations thoroughly, you've probably seen a note that indicates you should change your oil more frequently if you run your car in severe driving situations, and there may even be notes about using a different weight of oil depending on your climate.
Many mechanics, dealers and quick-change lube shops suggest 3,000-mile oil change intervals for many cars, arguing that most of today's American drivers operate their cars under what is considered severe driving situations. So-called severe-use driving situations include frequent driving in stop-and-go traffic, excessive idling, regular trips of less than five miles, frequent towing, frequent driving in extremely humid climates, and frequent driving in temperatures less than 10 degrees or more than 90 degrees.
While it is true many drivers experience at least one of these conditions regularly, it does not mean those drivers should automatically default to a 3,000-mile oil-change schedule, especially since the manufacturers' recommendations for today's cars range from 5,000 miles to 20,000 miles. Instead, follow the manufacturer's recommendations for severe use or, if your car has an oil-life monitor, simply change the oil when the system tells you to.
Another alternative is to spend about $25 to get your oil tested by an independent lab, which will provide an analysis of how much "life" is left in your oil as well as identify other engine problems. Use that analysis as a future guideline for the frequency of oil changes.
While changing your oil more frequently won't harm your car, it will put a dent in your wallet. Following the 3,000-mile rule, the average American would change his car's oil five times a year, yet the average manufacturer's recommendation could be anywhere from one to three times a year. That's a savings of at least two oil changes.
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