Oil unless it is dirty with abrasives will always lubricate properly. Diesel engines create abrasives suspended in the oil (soot) faster than their gasoline counterparts...Detergents are added to diesel purpose oils to separate soot and enhance lubricity. Studies here by many conclude 5,000 max oil-change on diesels....somewhat higher for gas using say Mobil-one. Dyno oils require more oil change frequency...depending on......alot!