DEAR CAR TALK: I bought a 2009 Honda Accord in 2009, which now has 125,000 original miles on it. I have never changed the oil or transmission fluid. The car still drives perfectly. What did I do wrong? – Rev. Marvin

P.S. What is an “original mile”?

P.P.S. Have you ever driven a car with at least one unoriginal mile?

P.P.P.S. I am 80, so please answer quickly.

RAY: I’m writing as fast as I can, Rev.

I can only guess that you have some higher mechanical connection that the rest of us don’t. Because failing to change the oil for 125,000 miles would croak most engines. The fact that your car is still running perfectly is a testament (sorry) to how well Honda designed and built it.

We’ve seen engines whose oil hasn’t been changed for only three or four years, and they’re already toast. The sludge and varnishes on the valve train would make you cross yourself in fear – unless you’re a mechanic with kids in college. Then, you’d say grace for what you’re about to receive.

So you can either go for the Guinness Book of World Records and see how long this thing will run without an oil change, or you can rush over to the dealer before it starts blowing blue smoke and trade it in while it’s still worth something. You can tell the dealer it has original miles and original oil.

The transmission fluid is less of an issue. In fact, lots of cars now don’t even call for transmission fluid changes; the transmission is sealed at the factory. But the engine oil – even superior synthetic oil – is supposed to be changed every 10,000 to 15,000 miles at most.

To answer your other question, Rev, there are several theories about the term “original miles.” There’s the theory that since odometers used to turn over at 99,999 miles, a car could show 25,000 miles and really have 125,000 on it. So the 25,000 would not be “original miles.”

A similar theory says it came from the time when it was much easier for a used-car dealer to roll back the odometer with an electric drill. So it meant “actual miles.”

But my understanding is that the term “original miles” dates back to when engines typically lasted only 50,000 or 75,000 miles before needing to be replaced or rebuilt. So if you had 80,000 “original miles,” that meant the car had its original, un-rebuilt engine in it.

Or, in other words, when you saw an ad for a used car that said “80,000 original miles,” you knew you’d be due for a rebuild on the way home after you bought it.

Got a question about cars? Email Car Talk’s Ray Magliozzi by visiting the Car Talk website, www.cartalk.com.