Ok, I understand the point - under 50* the metal is contracted and therefore a tighter seal, so you're wearing away metal that you wouldn't otherwise be doing in warmer temperatures. Whether or not this is true depends on the design of the engine and the tolerances. I would hope that the designers understand that these things will be used in sub-50* weather, and design the tolerances and alloys accordingly.

Now, I live in Vermont and we fly in sub 50* weather for like at least half the season, and have 'chili fun flies' off frozen lake champlain. No one has complained about engines losing compression while doing so. I"ve also been obsessively glued to this forum since last winter and have heard of no such thing as not using engines in the cold.

I know there are tons of guys who will read this and laugh, who live in colder states and use torches and lighter fluid 'cause it's too cold to start the engines otherwise.

Use the right lubrication and a hotter plug