Ask the Car Guy @socky April 13

I knew a girl whos parents lease their car instead of owning. They would return the car at the end of the lease and start a new lease with a new car. During that time that they lease the car, they never change the oil or do any maintenance. The car would have around 30,000 miles on it when returned. I can imagine how nasty the oil was in those cars when they were returned.

The need to change the oil really depends on the conditions and usage. I truly believe in changing the oil soon after the break-in period. Other than that, the oil change period stated in the owners manual should be followed.

Let's explore when and why you should change the oil.

The lubricating properties and additives break down over usage. In addition, contaminates get into the oil. These conditions are why the oil needs to be changed.

Let's consider my dirtbike for instance which I ride very aggressively. In a dirtbike, there is a "wet" clutch and a transmission that share the oil. Contaminates get into the oil from the vent and dirty environment that I ride in. Also contaminates get into the oil from the clutch that is in the oil and the wear from the transmission gears. In my dirtbike, the oil gets "dirty" much faster than it can possibly break down. It also only holds about a quart of oil. Instead of buying an expensive synthetic oil, I just buy the cheap oil and change it every few rides.

A car with a turbo or supercharger will create higher cylinder pressure which causes more leakage past the piston rings. This will introduce soot into your oil. On a turbo engine, you will find the oil turns black very quickly. Oil changes should be done more frequently on one of those motors.

On a car like yours with no turbo, you should have no issue with the guidelines in the manual. Synthetic is over and beyond what is necessary for a car unless the manual calls for it. Synthetic was actually invented for use in extreme cold environments. Synthetic typically is "slippier" than regular oil and can handle extreme heat better. Automotive oils actually have friction modifiers anyway. In fact, automotive oil can't be used in motorcycles because of those friction modifiers. The oil is actually too slippery and can cause damage to a "wet" clutch in a motorcycle.

Can a car go longer without an oil change? Absolutely. Is it safe to do it? If the oil is contaminated or the friction properties are degraded, then it could cause premature wear. It also depends on how sensitive your engine is to degraded oil. Some engines are built very robust. Others, not so much. On large equipment that use ridiculous amounts of oil, the owners may opt to have the oil tested periodically. This requires taking a sample to a lab to have it analyzed. They can determine by the sample if antifreeze is leaking into the oil, if the bearings are going bad, or if the oil is going bad. As long as the samples test good, they can skip the normal oil change interval. There are kits out there that allow the regular car owner to send a sample of oil to a lab, but that is overkill. Just change your oil at the regular interval.

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