I plug mine in pretty much any night it gets below freezing if I know I need it the next morning for sure. It doesn't really need it all the way up to freezing, but it sure makes it warm up faster. I've heard that if its below 10, you should plan on plugging it in.
AS far as how long to plug it in, longer the better. I plug mine in all night just cause I don't want to have to worry about it in the morning, but if you've got over an hour before you leave and think to plug it in, I would.
Oh, And I let it idle for quite a while if its not plugged in and its really cold. Generally try to wait to drive it until the needle moves a bit, and don't really get on it until it gets on the low end of the normal range...Plugged in, 10-15 min high idle. Not plugged in and really cold, 20+min high idle.
I've got a 6 pos chip and won't switch it out of stock programming until the temp needle gets to normal range. I don't know if it will hurt anything to run tunes when its cold, but I would just rather not push it...
Last edited by e99f2506sp; 11-03-2010 at 10:15 PM.