I am sure this is a repost but there are so so many posts i cannot find exactly what I am looking for. My 6.7 is up to about 110k and now that the warrenty is done I was thinking of maintaining the truck my self. Is the oil the dealer uses anything special? I know they use that low ash stuff? Should I start using the amsoil? Should I put synthetics in it (I have synthetics in the trans, dif, ect) are they worth it in the motors, if so which one? I also have an 06 5.9 with about the same miles would that be the same oil?