Are oil change recommendations a plot by oil companies to get more of your money?

Dear Car Talk

Dear Car Talk | Apr 01, 2001

Dear Tom and Ray:

Actually, this is a question raised by my husband. He was meeting with a patent attorney, and during the meeting the attorney turned to my husband and said, "Do you change the oil in your car?" My husband, thinking he was in a Fellini movie, said, "Of course, I change it every 3,000 to 4,000 miles."
"Fool!" said the attorney.
"Excuse me?" said my husband.
"Fool!" said the attorney. And then one more time: "Fool!"
The attorney claims that we only change our oil because the oil companies have perpetrated a dastardly plot against all car and truck owners in order to sell more oil. He claims he's never changed the oil in his 15-year-old car, and it runs better than it did when he bought it. Do you buy this? -- Leslie

TOM: Well, the attorney is right that the oil companies' purpose is to sell more oil. If they were being purely altruistic, they'd be using their TV ads to urge us to get more fiber into our diets.

RAY: But just because they're not altruistic, that doesn't mean you shouldn't change your oil. Scientifically speaking, we know that changing your oil makes your engine last longer. And when you look at the total pool of cars on the road, I think you have to dismiss the anecdotal cases, like the attorney's, of people who never change their oil and drive a car 600,000 carefree miles.

TOM: I'm sure you've also heard stories about people who smoke Camels and sleep on asbestos mattresses and live to 103. And the individual stories might even be true, but statistically, this lifestyle is not a good bet for you or me.

RAY: And the same is true for oil changes. Since motor oil is subject to thermal breakdown, dilution and contamination, the vast majority of people who change their oil on a regular basis will get more life out of their engines.

TOM: Most oil companies still recommend changing the oil every 2,500 to 3,000 miles. We used to agree, but we now think that's too often for the average driver. Years ago, we changed our recommendation to every 5,000 miles. And even every 7,500 is probably fine these days, due to the improved quality of both oils and engines.

RAY: I should mention that, as an experiment, I'm now in my second year of NOT changing the oil on my own '87 Dodge Colt Vista. And after two years, the only problem I've had is that the rearview mirror fell off. But if it wasn't such a heap already, I wouldn't be experimenting on it. If it were a REAL car, I'd change the oil every 5,000 miles.

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