Ron, I guess in reality I do just what you do. I take my rig to the local Ford dealer and have him do the oil change annually sometime in the spring. I usually put 5-7K on a year, so that stays in the recommended change interval. As stated, Ford Motorcraft oil is synthetic 5W20, but I'm not sure if it's full synthetic or semisynthetic. It really makes little difference. One thing that you might not know is that motor oils, even those with an oil company name, may be made by another manufacturer or by a number of manufacturers. Ford, for example, bids out their contracts and may change suppliers. What doesn't change are the specifications that Ford calls for in the bid. Gasoline is the same way. Mogas in the USA is now "fungible", meaning it all blended to the same federally controlled specs and differs only in the additive package. Pipelines carry huge volumes of gasoline from a variety of suppliers and it is additized at the wholesale terminal truck rack. Trucks coming in from different brand dealers get the same gasoline, but with different additives mixed in while the truck loads. Oil is made by much fewer refineries than gasoline and the different companies often buy base blending stocks from each other. In other words, specs are much more meaningful than brand names.
