Hello all. I recently came across this truck at my local Dodge Dealer and couldn't pass it up. I bought the truck for $8500 and will use it mostly as my daily driver (50 miles each way 4 days a week). The miles were piling up way to fast on my Cummins. Anyway, It runs like a truck with 40K on it and the miles have all been highway (obviously). It has an Multiple displacement system that shuts down 4 cylinders at highway speeds and apparently needs 5W20 for the system to work properly. Any suggestions? I bought it planning a new engine in the next year or two, But it runs so good I want this one to last as long as it can. Apparently the guy who owned it before me took good care of with synthetic changes at 6000 miles all done at the dealership. His commute was from Sauk Centre MN, To Minneapolis, about 110 miles each way. And I thought mine was bad. I was thinking about amsoil, But am open to suggestions.