1998 Avalon with 140,000 miles

My 98 Avalon with 140,000 miles started leaking oil on the road. I brought it in and the camshaft and a few other parts had to be repaired. The mechanic said that the car is not in the best mechanical shape and I should start looking fo ra new car. Question: My car has 140K and most of the other posters seem to have much more mileage on it. What is wrong with my car?

First, better get a second opinion. Second, has the oil/filter been changed often enough? Lack of oil changes or low oil levels are the main potential engine killers.