DETROIT (AP) _ Most major automakers agree: The adage that you should change your car's oil every 3,000 miles, or 4,800 kilometres, is outdated, and even 5,000 miles may be too often.
Ford Motor Co. became the latest manufacturer to extend its oil life guidelines, making public that it is raising the recommended oil change interval from 5,000 miles to 7,500 on its newly redesigned 2007 models and all subsequent redesigned or new models.
The company, like many other manufacturers, said that higher oil quality standards and new engine designs were responsible for the change, which affects vehicles driven under normal conditions.
``The oils have advanced a lot since the days when 3,000 miles were the typical oil drains,'' said Dennis Bachelder, senior engineer for the American Petroleum Institute, an industry organization that sets quality standards. ``They're certainly more robust than the oils of 10, 15 years ago.''
These days, motor oils start with a higher-quality base oil than in the past, and they have more antioxidants that make lubricating properties last longer and other additives that keep deposits from forming on engines, Bachelder said.
Pete Misangyi, Ford's supervisor of fuel lubricants, said the company conducted numerous fleet and laboratory tests with newer oils before it raised the interval.
``That allows more comfort, if you will, in extending the intervals using the new oils,'' he said.
Some manufacturers, such as Honda Motor Co. and General Motors Corp., have stopped making recommendations on all or most of their models, instead relying on sensors that measure oil temperature extremes and engine revolutions over time to calculate oil life and tell drivers when to get the lubricant changed. Oil can lose its lubricating properties if it runs at too low or too high of a temperature.
Peter Lord, executive director of GM's service operations, said oil can last 12,000 miles, about 19,200 kilometres, or even more for many drivers who don't run their vehicles in extreme heat or cold or tow heavy loads.
``It really does depend on the individual customer and how they've used the vehicle,'' he said.
Ford said it has found that its customers like a set mileage for service rather than wait for a sensor to tell them what to do.
For those who don't believe the sensors, Lord says GM has reams of data showing that they're reliable, and they notify drivers far in advance of when a change is necessary.
``We are absolutely confident of the technology. We back it with a 100,000 mile powertrain warranty now, so there's no doubt in our mind that this technology works,'' he said.
The longer oil life can save customers money. Ford estimates that drivers would save $600 over a five-year period by going from 5,000 miles to 7,500 between oil changes.
``From an environmental perspective we can save an enormous amount of oil,'' Lord said. ``There's no point in wasting precious oil changing it prematurely. And we don't have to dispose of so much waste oil, either.''
When to change oil is not without controversy, though.
Toyota Motor Corp. reduced its change interval from 7,500 miles to 5,000 in 2004 in part because it found that more drivers ran their vehicles under severe stop-and-start and short trip conditions that cause oil to deteriorate more quickly, said company spokesman Bill Kwong.
Toyota also had an oil sludge buildup problem on less than 1 percent of its 1997-2002 model year vehicles, Kwong said. Changing the oil more frequently prevents the sludge problem, which he said was caused by owners going more than 7,500 miles before changing oil.
The company lengthened warranty coverage on the affected engines to handle the problem, even before some owners filed a class action lawsuit, Kwong said.
Nissan Motor Co. recommends changing oil in its Nissan and Infiniti vehicles every 7,500 miles or six months _ unless the vehicle is used mainly for towing, trips of five miles or less in normal temperatures, 10 miles or less in freezing temperatures, stop-and-go driving in hot weather or low-speed driving for long distances, in which the oil should be changed every 3,750 miles or three months, spokeswoman Katherine Zachary said.
And for some engineers and mechanics, 5,000 miles is too long to wait.
Drivers must take the weather and how much freeway driving they do into account before deciding when to change their oil, said Danny Beiler, part owner of an auto repair garage in Sarasota, Fla.
Highway driving is less harmful to oil than driving in the city, but in Sarasota, the heat places nearly all cars under severe driving conditions that warrant more frequent changes, Beiler said.
``I have a problem with telling people 7,000 because you know they're going to go over that. I'd rather err on the side of being cautious and tell them to do it early.''
Dewey Szemenyei, marketing manager for passenger car motor oil additives for Afton Chemical Corp., said he still changes the oil in his 1998 Toyota Sienna minivan every 3,000 miles.
``I really feel it's great insurance,'' said Szemenyei, whose company makes additives that go into motor oils and who chairs a Society of Automotive Engineers committee on engine lubrication.
``There's not what I consider a right answer. However, if you go with the owner's manual recommendation you should in general not have any problems,'' he said.