No scheduled maintenance on Ford Superduty

Fluid change intervals for automatic transmisison fluids are related to fluid oxidation/fluid additive depletion over a test cycle that is meant to represent an assumed worst case operating pattern for the oil. The ULV fluid utilized in the 10R140 utlizes a very refined base oil (Type III base stock) that results in a very stable fluid with stable viscoisty over the life of the fluid. It is this hihg quality base stock combined with the fluid's additive package that defines the lifespan of the oil. The stability of this oil is what drive's the high mielage fluid change recommendation. While changing fluid more often may seem like a good thing, fluid changes do carry the risk of introducing contaminants into the system, particulary if the shop does not use fluid exchange equipment. Modern automatic transmission controls are very sensitive to small particle contaminants so a shop that is not careful wtih their fluid change procedures runs the risk of introducing contaminants into the transmission fluid that can be detrimental to the valve body resutling in valve silting and sluggish valve operation. For this reason I generally am not a fan of early fluid changes unless the fluid has been subjected to a severe duty cycle (extended towing at maximum vehicle capabiltiy in high ambient temperature on grades, for instance).