actually, ford specifies that 5W20 should be used. i would NEVER reccomend using anything more than 5w30. the ford 5w20 is a synthetic blend and is is required because if the tight machining tolerances on the modular engines-or the engine wont get proper lubrication. also, being that i work at a ford dealer as a service advisor, and was a technician, i know that ford WILL void a warranty if there is an engine problem due to using the wrong weight of oil. the only ford vehicles that use 5w30 are the ranger and explorer with the 4.0 SOHC, which will soon find its home in the base model mustangs. just figured i would pass on the info for anyone who has warranty.
frank