I've never said anything at all about changing the oil every 3,000 miles. And I'd say engine wear is highest when the engine is brand spanking new when they drive it around the factory/docks/ports and those first few miles you put on it. When you change the oil you're not sucking the engine bone dry. There is still going to be oil on the various engine parts, just as there would be if you turned the engine off and restarted 30-60 minutes later.