A stalled car on the shoulder of the road has slowed down the traffic. Seeing its hood open makes you wonder when you last had your oil changed. The windshield sticker from the auto shop says 3,000 miles, your owners manual says 7,500 miles, and some government agencies are encouraging even longer. Which is correct? There are a few factors that must be considered in order to make an informed decision.
What’s at stake?
The issues involved in the frequency of oil changes range from personal to global. On the surface, it appears that the more often you change your oil, the more it will cost you. That’s not entirely true. Too long between services could cost you in the long run with increased wear on the engine, lower fuel economy, and the potential to void the warranty. On a grander scale, unnecessarily cycling through oil has a greater environmental impact, from pumping it out of the ground to its disposal.
What does oil do?
Oil has two primary functions in an automobile. First, it lubricates the moving parts, and in conjunction with the filter, removes debris created by friction. Second, the oil helps dissipate the heat caused by friction. Over time, oil loses its ability to perform these functions resulting in the loss of horsepower and fuel economy.
Factors that affect oil life
Type of oil, type of engine, and type of driving are all factors that affect oil life. A Diesel engine or a turbocharged engine runs hotter than a gasoline engine, degrading the oil more quickly. High mileage cars (over 75,000 miles) consume oil at a higher rate. Short, frequent trips will stress your oil more than highway miles, and dusty roads will add debris. These are all considered severe driving conditions. If you check your oil properly, you can add time between oil changes. Synthetic oil will maintain its integrity longer than conventional oil due to its high refinement and additives.
Do you really need to change your oil every 3,000 miles?
Probably not. Listen to your oil life monitoring system, if you have one. If not, Consumer Reports suggests 7,500 miles for most driving, but shorter intervals for severe driving conditions. If after all these considerations, you are still unsure, don’t worry. Most Americans are just fine changing their oil every 5,000 miles.