this issue may have been beat to death in the past, however I need to revive it for just a moment.  I was given Castrol 20w50 motor oil recently.  The weather is beginning to warm a bit to now a high of 72.  Is this still too low an ambient temperature to use 20w50 or should I wait until the temperature reaches the 80-90's (82 air cooled engine)?  Also is a thicker oil more appropriate for the air cooled engine?

tim