The 4.0 was excluded from the 5W20 back spec, it still requires 5W30. As far as finding a list of vehicles for the back spec you can find that in Ford's TSBs. Sorry I can't give you anything more specific than that, but that is where I found it.
FWIW: This was posted on another site some months ago regarding the Ford 4.0 V6 by someone who is supposed to be from the oil industry and seems to know a lot. Don't know if what he says below is true, but thought I would share it with you:
quote: We discussed this subject at a meeting two weeks ago. We are of the opinion (notepinion) that Ford has been having issues primarily with the 4.0 engine in the valve train. The reduced add packs have not been helpful and premature wearing of certain models has been recorded. Until the 4.0 engine is replaced in the next two years (supposedly), I expect the SL oils to be available. This can be used as leverage should a class action suit occur which I doubt will happen. Again, this is all opinion- no concrete facts.
And in another thread the same person posted:
quote: Your 4.0 requires a 5w-30 oil. If I were looking to maximize the life expectancy of the engine, I would be running an SL oil, if you can find the old stock (current production is SM), and I would be adding a half bottle of Valvoline Synpower oil additive. It is loaded with ZDDP which is a multifunction additive. Your 4.0 is a high stress engine and can use all the help it can get. Following this regimen, your engine should coast pass the next 100,000 miles and far into the next 100,000.
My wife HAD a 2002 Explorer with the the 4.0L 6cyl. It got "babied" but after 40,000 miles it fell victim to the timing chain tensioner failure Ford knew about for years but ignored. The iron level in the oil UOA spiked really high. Ford's answer was to charge well over $2000 to replace the tensioners with the same ****** parts! She traded it for a 2005 Eddie Bauer with the 4.6 V8. Bought it during the "employee pricing" and actually paid less for a loaded 2005 V8 EB then for her 2002 XLT V6. Which was $200 above Ford invoice at the time.
During it's life I used MC 5W-30 and Schaeffer's Supreme Blend 5W-30 with LC. Other than the iron wear #'s going sky high, the Schaeffer's & LC UOA wear #'s were real good. Too bad because otherwise it was a nice SUV. But I wasn't going to pay over $2000 and have the same problem return again.