When I check the Oil on my 250 chevy motor, I have been finding a coat of foam on the Oil Filler Cap, and sometimes on the dipstick.

I changed the oil last week and the oil still looks good.

The foam is just there when she is cold.
Lately in Arkansas we have had overnight lows in the 40's and 50's

Have you had it checked for rabies? (sorry, couldn't resist).

I have heard of auto-trannies foaming from over filling but can't remember hearing of your engine condition.

Pinebluff,
The foam is a result of condensation. Cooler weather and short run times do not allow the engine to get upto a sufficient operating temp to boil out the water accumulated from condensation.

The fix is hard, drive it more! Tom

Dude, in addition to Toms suggestion be sure that the PCV system is functioning correctly and check the thermostat....I run 195 all year with no problems .....fats

This is actually one of the causes Tom alluded to. If the PCV isn't properly evacuating, you'll get more condensate buildup. Which reminds me... time to check my PCV.