Let me put it this way: when I changed the oil in mom's 01 ZX3, I used Mobil 1 5W-30 even though it came factory filled with Motorcraft 5W-20.
Ford is using the 5W-20 to improve CAFE averages and sell more oil - I'm not sure any other brand has a 5W-20 on the market yet, but I see Motorcraft 5W-20 on the shelves in some places.
It is my opinion that this is at the cost of long term reliability, so I'm not buying.
