I have an '02 Explorer with the same motor in it. I've been using mobil 1 ep for about 10 years in it, and my oci is anywhere between 10-12 k miles. I've never done a UOA on it, but it has 180k miles on it, idles and runs like new, doesn't use any oil between changes, and doesn't have any funny startup noises. I don't think those motors are particularly hard on oil, at least that's my experience.I'd like to get another 100k out of it before I have to replace it. But in reality , I would bet the trans or something else will go before the motor does.,,,