Ken04,
Thank you for your input.
They have full synthetic but availability is in question though.
http://www.motorcraft.com/products.do?item=15
Off the topic, BTW I hope your import minivan is not a Nissan.
With Mobil1, I don't see any sludge build up on my wifes Honda (traded in for the Stang) and my truck. However, evaporation rate is high as you mentioned, and I've seen it.
From Ken02's input, there are no issues with the Motorcraft synthetic blend.
I know the Motorcraft filter is good, which I've always used on the '67.
I just took a look at the owner's guide, and it's calling for Motorcraft 5W-30 Premium synthetic blend.
My conclusion is to go with the Motorcraft synthetic blend and the Motorcraft filter.
I could finally make up on my mind on this silly "what oil to use" issue.
Thank you everyone.