Factory manuals recommend 20/20W and 5W for less than freezing temps For multi viscosity they do recommend 10W-30

http://chevy.oldcarmanualproject.com/shop/1949_53/00lube/0_2.HTM
http://chevy.oldcarmanualproject.com/shop/1955truck2/55ctsm0002.htm

Oil viscosity is determined at 100C (boiling point of water).. not 'cold'. So thinner oil will always flow better at start up.

My preference is 5W-20 or 5W-30 dino oil. Wally World brand (supertech) is highly rated and inexpensive.

Last edited by pfarber; 10/08/2014 6:32 AM.