I STILL remember learning from my father how to carefully remove a dipstick to check the oil level in our cars. It was drilled into me — along with turning off the lights when you left a room and clearing the plates off the table after dinner — that oil needs to be changed every 3,000 miles or so.
But sometimes, we need to throw aside our parents’ good advice. In March, for example, I wrote about how we should relearn the dishwasher and laundry soap habits we inherited from our mothers.
Add frequent oil-changing to that list.
“There was a time when the 3,000 miles was a good guideline,” said Philip Reed, senior consumer advice editor for the car site Edmunds.com. “But it’s no longer true for any car bought in the last seven or eight years.”
Oil chemistry and engine technology have improved to the point that most cars can go several thousand more miles before changing the oil, Mr. Reed said. A better average, he said, would be 7,500 between oil changes, and sometimes up to 10,000 miles or more.
The California Integrated Waste Management Board ran public service announcements for several years about “the 3,000-mile myth,” urging drivers to wait longer between oil changes. Although the information is a few years old, the board has a list of cars on its Web site and how often they need oil changes. The concern is not only the cost to drivers, but the environmental impact of throwing away good oil, said Mark Oldfield, a recycling specialist for the agency.
But the situation is not that clear cut, according to Robert Sutherland, a Pennzoil scientist who works at Shell Global Solutions.
Rather than picking a number, Mr. Sutherland said, he recommends following what your owner’s manual advises. Things to consider when evaluating your driving include a lot of stop-and-go driving, short distances, extended idling, muddy, rough or dusty roads or really humid or cold temperatures. A person who does alot of stop and go driving may need an oil change every 5,000 miles, while a person who does a great deal of longer-distance highway driving may go every 7,500 miles.
The different types of driving are usually known as severe and mild (which is also sometimes called normal), Mr. Sutherland said, which seems counterintuitive since most of us probably don’t think we drive in severe conditions. But we do.
The reason, he said, is that if you take a trip of less than 10 miles or so, the engine and the oil are not completely warmed up. And if the oil is still cool, he said, it cannot absorb the contaminants that come from internal combustion as efficiently.
“It’s designed to work best when fully warmed up,” Mr. Sutherland said. “If you’re running to the music lesson, to school, the gym, that’s severe driving conditions.”
Mr. Sutherland said he has a mild commute. “It’s 47 miles, all highway.”
What actually happens if you don’t change your oil? Well, it doesn’t run out, it simply gets dirtier and dirtier. It’s like mopping the floor with a bucket of water and detergent. The water starts out clean, but the more you use it, the filthier it gets. Eventually, you’re making the floor dirtier if you don’t change the water.
“Very often, it is the case that they’re changing their oil too often,” she said. “They do what their dad did with his ’55 Chevy.”
Another way to get a more accurate assessment of your oil needs is to buy a car that has a maintenance minder. GM cars with OnStar Vehicle Diagnostics will even send you an email letting you know if you need an oil change. The time between oil changes varies depending on the driver and driving conditions.
So before you go in for your oil change, dig out your owner’s manual and see what it says. And then, go get the car washed. That’s one thing that always seems to be needed.
