09-19-2015, 08:14 AM
Frictional losses when cold aren't solely due to poor oil circulation, but are related to thermal characteristics. Most pistons are "cam ground" meaning the piston isn't perfectly round (like the cylinder) when cold, but is as close to being perfectly round when the engine has reached it's designed operating temperature. This is why cold engines are designed to idle at a higher rpm when cold, to overcome frictional losses. Cold start-ups are the worse. I believe engines actually get hotter for a short period after shut-down. When stopping after riding for a period of time, I let the engine idle to allow for temperatures to equalize to the greatest extent possible, then if it looks like it's gonna' be awhile (train, construction, accident), I'll shut it off.