Many studies over the years lead to the conclusion that that over the life of an average driven automobile, about 80 percent of engine wear occurs during warmup. Once the engine is at operating temperature wear is virtually unmeasurable. It's too bad that cars don't remember the number of cold starts and service history. These data are much more relevent to engine life than mileage

Long trips at normal freeway speeds are about the easiest service that a car can get. Even in warm to hot weather there is sufficient air flow to keep coolant, and particularly oil temperatures at near ideal levels.

Thus, when looking at 15 year old cars, the high mileage salesman's car may have a better engine than the "little old lady's" car, but the latter will always look better cosmetically because it spends most of it's life in the garage. Yet, all those cold starts and short trips take a real toll inside the engine.

Duke