When it comes to motor oil the one thing we can all agree on is that we will never agree on which is the right oil for a Model T.
It seems the management of one oil company has picked up on this and produced a range of oils to satisfy all of us on this forum.
Racing Oils from a straight 2w to a straight 70w, see:
http://www.redlineoil.com/content/files/tech/Race%20Oil%20PDS%206-12.pdf
http://www.redlineoil.com/Products.aspx?pcid=1
Normal Oils, see:
http://www.redlineoil.com/Products.aspx?pcid=21
I guess with straight 2w and 5w oils now available there's nothing stopping us from taking our cars across the Bering Strait next time it freezes over.
Until you go to the product info then you see it is a multi-grade
"Each race oil product is a multi-grade, offering 2-4% more power than oil of a similar viscosity - 20WT is a 5W20, 30WT is a 10W30, 40WT is a 15W40, 50WT is a 15W50"
The 2w, 5w, 10w and 70w racing oils are monograde, just like the "good old days".
Correction, it seems the 5w is a 0w-5, and the 10w is a 0w-10. The 2w and 70w seem to be the only monograde. The 2w it is then for the Bering Strait.