In article ,
"Dennis O'Connor" wrote:

I started my engines this morning at -4 F... No preheat never do No
problems; though it did take 6 blades each, before they fired - mucho cold
senor... Use 15W50... I get oil pressure indication in less than ten
seconds... That's the way this airplane has been treated ever since
semisynthetic, multiviscosity, oils came out.... Engines go to TBO
routinely...
denny

Wow. To each his own. I would never start at those temps without
preheat, and I also used 15W50. I've also tried to pour it when it's
cold. G If it works for you, great.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html