Dealer put 5W20 insted of 5W30
#12
#14
#15
Ford did back-spec a lot of engines to 5w-20, but the SOHC 4.0 was not one of them. That oil is too thin for that motor, I'd switch it out immediately! I'd also go back to the same dealer and have them fix, and document, it. I'd also ask them to provide some documentation that 5w-20 is acceptable for that application.
#17
#18
Going up a weight is fine, although your fuel economy may decrease slightly. But going down a weight is risky to the engine, the oil may not be robust enough to adequately protect the engine. There is a reason that engine was not back-spec'd, and I'd bet that the Ford engineers know more about the lubrication requirements of that engine than the oil change kid at the dealership. Why not be safe, and return it to the dealership and have them correct their mistake?
#22
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