The oil you put in your car does a lot more than just lubricate the motor. It helps keep the engine cool, prevents corrosion and can improve fuel economy by reducing friction between the moving parts and keeping the engine clean. In other words, the oil that goes into your car is not just oil. It’s a combination of the following additives which account for 10-25 percent of the product used:

In addition, the viscosity index (indicated by the grade of oil used) serves to keep the flow-ability of the oil over a wide range of temperatures.

The two most commonly used grades are 5W-30 and 10W-30. The lower the number (5), the thinner the oil, indicating how it flows at low temperatures. The ‘W’ means the oil can be used in winter, and the second number (30) refers to how well it flows in high temperatures. Thus, oil used in warmer climates will have a higher second number than that used for driving in colder temps.

Remember, the viscosity grade is important, and the recommended grades vary for make, model and year of each vehicle, so before you buy any oil for your car, be sure to consult your owner’s manual. The wrong oil can severely damage the engine. It is also important to check your oil level at least once a month, adding oil, as needed. If your car’s motor lacks enough oil, the engine will seize and your car might just as well be used as a planter for your geraniums!

Complete oil changes are not needed as frequently, and, in fact, modern oils don’t need to be changed as often. Still, the recommended time frame for “severe” driving (i.e., frequent trips of less than five miles, stop and go traffic, dusty, or extremely cold weather, towing trailers or extended idling) is every 3 months, or 3,000 miles—whichever comes first.

For those who do more long distance driving, allowing their cars to “blow out” every 6 months or 7,500 miles is generally sufficient. However, special engines such as turbo-charged engines and diesel, may require more frequent oil changes. Again, it is always a good idea to consult your owner’s manual. Remember, if you take good care of your car, it will take good care of you for many years.

P.S. Although Consumer Reports’ extensive testing failed to show any real superiority or inferiority between different brands of oil, you should be sure that any oil used in your car carries the label: “For Gasoline Engines,” and that, the bottle bears a starburst label, meeting API requirements.

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