I drive a '71 Dodge Van Class C motorhome with a 440 from a 78 van. I drive it less than 10k miles a year, and start-ups are about every 2-4 months. Any thoughts about what oil too use? When driven, the miles are easy, if I tow anything it's a 2500 lb boat/trailer, the trans is a 727 Torqueflite with a Gear Vendors over/under drive. Typical highway speeds are about 60 mph.