For all, please give me some advice. I realize this topic will be highly controversial due to brand loyalty etc....here is the scenario; I am buying a used 1999 F-250 XLT with a 5.4 Triton. The truck has had the engine replaced about 50 K ago with another 5.4 Triton and Ford doing all of the re-install on the motor. Underneath this thing is as dry as a desert! NO Leaking, etc. I have test driven the truck, it is smooth as silk,motor sounds great and everything appears in fantastic working order. With that said, the one thing that was a "bummer" for me was the fact that the owner was using Pennzoil 10-30 in the truck since the motor was replaced. He has been good about regular oil changes, so with that being the case, even though Pennzoil was his oil of choice I'm sure it is o.k. being that changing it regulary is the most important thing. However, Penzoil is NOT my personal choice at all. I wonder what the opinion is regarding changing oil brands with a higher mileage engine like this..will it hurt anything?... and what would be the best recommended weight/ viscosity for the 5.4 Triton? Would switching to a full synthetic like a Mobil One be a good choice over the conventional? Please feel free to weigh in.
Second, there is no "best" as many people will try to tell you otherwise. However, many of us have favorites. Personally I am running Shell Rotella full synthetic. Amsoil, and Chevron are also popular brands. I have also run the Motorcraft oil with success.
My best advice is dont listen to us, listen to your truck. Try a few different oils and see how your truck responds. You will be surprised how much your truck can tell you. Using a Blackstone Labs test kit you can get a detailed oil analysis that will tell you everything you need to know. Thats not necessarily, but good for the truck owner who cares. Try 3 or 4 different brands changing at 5000 miles until you find the oil you and your truck agree upon. A full synthetic will be better for your truck, but a normal oil like the Motorcraft oil will also be just fine. In my opinion no single oil is the best, but rather each truck is just a little different in its tastes. See what your truck likes.
Also, as far as filters go, I would stick with Motorcraft oil filters. They seem to be at or above par most of the time.