Is idling the engine with the AC on hurting my 150k mile Corolla?

Dear Car Talk

Dear Car Talk | Jan 01, 1999

Dear Tom and Ray:

My husband is retired. And since we enjoy each other's company very much, he
always goes to the grocery store with me. While I shop, he stays in the car
reading books. The problem is in the summer. In order to keep cool, he keeps the
engine running and the air conditioner on. I spend between 30 and 60 minutes in
the store. Our car is a 1988 Corolla with 150,000 miles on it. Is this practice
doing bad things to the car? -- Joan

TOM: Joan, if he enjoys your company so much, why isn't he in the grocery store
WITH you? Seems to me he could stay nice and cool by hanging out in the frozen-
food section.

RAY: Actually, he's not doing any harm to the car. Idling creates very little
wear and tear on the engine. Ask my brother. He's the King of Idling.

TOM: When the engine is idling, it's turning slowly. The explosions in the
cylinders are smaller, it's running cool and there's very little load on the
bearings. In fact, if I had to take a wild guess, I'd say an hour of idling is
equivalent to about five or 10 minutes of highway driving in terms of wear and
tear (someone who's done a Ph.D. dissertation on this will send us the exact

RAY: It does waste a little gas and does create a little more pollution, but
idling in the parking lot for an hour won't damage the car.

TOM: And think of the alternative, Joan. Without the air conditioning, after an
hour in the car, his BO would wilt your nice, fresh, newly purchased lettuce!

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