During the miles between oil changes, the oil in your vehicle's engine gradually becomes contaminated with dirt, soot, metal particles, gasoline and many other impurities. As mileage accumulates, so do the contaminants in the oil. Eventually, the oil will be contaminated enough that the filter cannot remove them effectively and the oil cannot keep them in suspension. When this happens, the oil turns to sludge, and the sludge can adversely affect the life of your engine. Today, many car manufacturer's are recommending oil changes every 5,000 to 7,500 – or even every 10,000 miles – for many cars operating under "normal" driving conditions (more frequently for those driving under "severe" driving conditions).

According to the owner's manuals of many new cars and trucks, “normal driving conditions” mean operation of the vehicle for at least 20 minutes at medium speed with a steady throttle in a clean environment.

However, if you drive under "severe driving conditions”, your vehicle's owner's manual may recommend an oil change every 3,000 miles. Following is the typical definition of "severe driving conditions” – does this define your typical driving?

• Repeated, short distance driving
• Extended periods of idling or low speed operation
• Extensive use of brakes
• More than 50% of your driving occurs in heavy city traffic during hot weather over 90°F
• Driving for a prolonged period of time in cold temperatures and/or extremely humid climates
• Driving in dusty conditions or sandy areas
• Driving in areas where salt or other corrosive materials are evident
• Driving on rough or muddy roads
• Driving in mountainous regions

Do synthetic oil blends better engine performance and provide added engine protection? Despite better performance, synthetic additives wear out just as with conventional motor oils and need to be changed just as frequently.

What about just changing the oil filter? Does that prolong the period between oil changes? Changing the oil filter is great, but the oil still must be changed along with it. The filter can only capture the bigger particles suspended in the oil, not replenish the spent additives in dirty motor oil.

Again, the key is the "normal" or "severe" driving conditions question. Which are you driving in?

Extending the oil change interval for your vehicle beyond that which the manufacturer recommends can seriously shorten the useful life of your engine and cost you several times the incremental savings you gained by less frequent oil changes over the life of your vehicle.

Are you in doubt? Just ask any professional service technician how often they change the oil and filter on their own personal vehicle. Chances are - their answer will be every 3,000 miles.

Don't push the limits of motor oil and risk damaging your vehicle's engine, especially when the incremental gains over the life of your vehicle are relatively minor. Trust your engine to the experienced knowledgable professionals ready to assist you at Duke of Oil.