DEAR CAR TALK: When I bought my 2011 Toyota Camry, the dealer told me that the synthetic oil didn’t need to be changed so often, say only about every 10,000 miles or so.

Since I had free service at the dealer initially, I took it there for regular maintenance, and despite what they told me, they kept changing the oil and filter much more frequently than they said was required. I didn’t care, since I wasn’t paying for it.

Once my free service visits ran out, I started taking it back to my regular mechanic, who changed the synthetic oil every three months. Since the synthetic oil is more expensive, when my husband asked about this, one of the other guys at the shop (not the head mechanic) told him, “The dealer just wants you to ruin your engine and buy another car!”

The head mechanic suggested I could go 5,000-6,000 miles between oil changes, depending on the type of driving. Yet the reminder sticker they put on my windshield is again for 3,000 miles.

I pointed out that the mechanic might want us to pay extra, more often, for the more expensive oil changes that aren’t necessary. What’s the real deal with synthetic oil? – Susanne

RAY: The dealer is right. Unless you drive the car extraordinarily hard – like using it as a taxi in Phoenix in the summer – synthetic oil is designed to go about 10,000 miles between changes. Changing synthetic oil every 3,000 miles is far too often.

As mechanics, it takes us a while to catch up with reality. Oil changes used to take place every 1,000 miles. And it took years before mechanics accepted that 3,000 miles between changes was OK.

So there’s a lag in acceptance among mechanics that synthetic oils are really far superior to conventional oils.

If you want to be extra safe and err on the side of caution, I’d say you can change your synthetic oil every 7,500 miles, which is the typical service interval for lots of cars anyway. But I wouldn’t hesitate to recommend that most of my customers go 10,000 miles.

While changing it any more frequently than 7,500 won’t harm anything – except your bank account – it’s really not necessary.

So buy a bottle of Wite-Out, Susanne, and keep it in your glove box. And then every time you drive away from an oil change, just change the mileage on the reminder sticker.

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