Opinions come from a variety of sources: our dad, the quick-lube guy or maybe a magazine article. Problem is, they don't all agree. Not even close.
Some swear by the 11th commandment, "Thou shalt change thy oil every 3,000 miles." But nowadays, many say that's a waste of money. You need to change oil about every 7,500 miles.
"The vast majority of American commuters are changing their oil way too often and wasting a lot of money in the process," said Philip Reed, senior consumer advice editor for auto website Edmunds.com.
The good news with many late-model cars is you don't have to decide at all. Your car has a monitoring system to tell you when it needs an oil change.
Here are some questions and answers to help you change oil often enough to protect your car but not so often that you're wasting money, with help from Reed; Gary Pollak, program manager of technical projects at the Society of Automotive Engineers; and Pam Oakes, a technician certified by the National Institute for Automotive Service Excellence. She is also owner of Pam's Motor City Automotive in Fort Myers, Fla., and author of the self-published book "Car Care for the Clueless."
WHY CHANGE OIL? Besides the obvious job of lubricating metal parts of an engine, oil also acts as a coolant by reducing friction and dispersing heat. It's also a cleaner, trapping tiny particles. Oil becomes dirty and doesn't work as well over time. So you need to drain the old stuff.
Where does the 3,000-mile rule come from? This used to be the standard, and a good one. "It was true when our father told us that," Reed said. But things have changed. Both engine technology and oil formulations have improved, allowing you to travel longer between oil changes.
Still, repair and oil-change shops confuse the issue. They affix to your windshield what Reed calls "that horrible little sticker" as a reminder to change oil in three months or 3,000 miles. "People are really busy, and they rely on the sticker, but it's really a marketing tool," he said. "It sort of appears to be whispering in the corner of your brain. I just tell people to peel it off."
The shops are in the business of selling you more oil changes, and in some cases, they want to get you in the door to sell you other services, such as fluid flushings, or products, such as fancy filters, he said.
An Edmunds.com investigation into the truth about oil changes last year offered a blunt conclusion. "This wasteful cycle continues largely because the automotive service industry, while fully aware of the technological advances, continues to preach the 3,000-mile gospel as a way to keep the service bays busy."
Oakes, a dealer and auto technician, concedes this is true at some repair shops.
HOW OFTEN SHOULD I REALLY CHANGE OIL? The average car's oil change interval is 7,800 miles, Edmunds found. Consumer Reports says most people would be fine changing oil every 7,500 miles or six months. But averages don't necessarily apply to your car. The best rule is this: Check the maintenance section of your manufacturer owner's manual. Look up this information once, and you never have to worry about it again for that vehicle.
What about "severe" driving? This is the loophole through which many repair shops drive their overly cautious advice about 3,000-mile oil changes. While an owner's manual might recommend changing oil every 7,500 miles; it might also say if you drive in "severe" conditions, you should change oil every 3,000 miles. So, it can come down to the definition of severe. "There's a lot of disagreement over what severe means," Reed said.
Idling, for example, is considered a severe condition. But does that mean idling for 20 minutes waiting to pick up a child from school, or idling for four hours?
Reed's advice? "Severe means severe," he said. So that means off-roading in the desert, towing heavy loads or really abusing a vehicle - think taxicab or delivery van, he said.
SHOULD I TRUST THE DASHBOARD OIL-LIFE MONITOR? Yes. Newer vehicles have monitoring systems for oil. For 2010 vehicles, 14 of 35 carmakers had oil-life monitoring systems, Edmunds says. These systems have sensors that monitor your driving and certain vehicle conditions, such as temperature in the drivetrain. Based on that information, the system uses an algorithm to estimate how dirty the oil is and alerts you when an oil change is needed. Typically, the warning gives you plenty of time to get around to scheduling an oil change. Edmunds.com, using oil tested by an independent firm, found oil-change warning lights went on about 2,000 miles early.
What if I drive very few miles? That's why recommendations often come with an interval for time as well as miles. It's a good idea to change oil at least annually, even if you don't hit the mileage interval, because moisture can build in the crankcase, making oil less effective, Reed said.
IS IT A PROBLEM IF I CHANGE OIL TOO OFTEN? It won't harm your vehicle, but America's oil-change addiction has many consequences. First, you'll spend more time and endure more hassle changing oil more often. And you'll spend more money on oil changes and whatever else the repair shop can talk you into.
There's an environmental impact too. The California Department of Resources Recycling and Recovery even sponsored a public education campaign about it. "Following the 3,000-mile myth generates millions of gallons of waste oil every year that can pollute California's natural resources," it says on its website. It says only 59 percent of used motor oil is properly recycled. The rest, with its heavy metal and toxic chemicals, often ends up in waterways.
Bottom line? Save time, money and Mother Earth by knowing your proper oil-change interval and, most likely, changing oil less often.
ULTIMATE ARBITER?
Don't trust the so-called experts or even your owner's manual about how often you should change your motor oil.
You can pay to have a sample of your oil tested. Like sending a blood sample to a lab, the results will tell you a lot about the fluid, including how many more miles you could have used it.
An example of a testing company, the one Edmunds.com used, is Blackstone Laboratories, blackstone-labs.com, of Fort Wayne, Ind. Its test costs $25. Another is Indianapolis-based Polaris Laboratories, polarislabs1.com, which charges $26.99, according to a customer service representative.
ABOUT THE WRITER:
Gregory Karp, the author of "Living Rich by Spending Smart," writes for the Chicago Tribune. Readers may send him e-mail at gkarp@tribune.com.
Read more: http://www.newsobserver.com/2011/02/27/1017582/spending-smart-change-oil-after.html#ixzz1FGpENaEr