My Daily is a 2000 Buick Century with the 3.1. It had 24k on it when I inherited it 5 years ago and has 108k on it now. It gets 5w30 High Mileage SynBlend in different flavors. Valvoline Maxlife, Castrol GTX, Providence (rural king). OCI’s are 5k. Engine doesn’t use any amount to speak of...