Some years back Consumer Reports did a survey of lon lived cars and what the owners did to get that far. They found adirect relationship between oilchange interval and engine life. Of those who changed oil every 3000 miles or less, only 15% had internal engine problems, while of those that changed oil at 5000 miles or more, 26% had internalengine problems. These were car owners who got their vehicles up to 250,000 to as high as 548,000 miles. Even then, their recommendation was; oil is cheap, engines are expensive.