Motorcraft = excellent 5w20. one of the best, and im sure everyone would agree. if it was still $14 a jug many of us would still be running it.
its the $19 a jug now that makes us consider QSUD/PP instead. although im not convinced either one actually outperforms motorcraft.
as far as the 20wt discussion im going to pull with TRAV on this one and say that the correct grade the engine was originally spec'd for is probably the safer choice. no way am i going to dump Toyota 0w20 in my S2000 and trust it to be ok. that's silly, its spec'd 10w30 or 5w40 for a reason. i dont believe any grade of oil is a cover all vis.