I moved from Southwest Virginia to Southwest Georgia, it get's pretty cold here during the winter. It's been snowing in part of Northern Georgia the last few years. But it doesn't get -30

 

I wait 5 min or so until the thermostat cycles once. My reasoning is that it's best to wait to operate it until after any thermal expansions have happened but am also impatient too. The single thermostat cycling timing is a compromise between the the extremes of no warmup and totally warmed up.

 

But isn't it bad to drive a very cold engine because it is UNDER LOAD?

I thought that was the whole reason of warming up the vehicle. To get it to a neutral temp before it is under load.

 

I'd say no. As soon as the engine starts and oil pressure is established, I don't see how gently driving it will harm anything. I just can't think of any physical reason why an engine has to be at normal operating temperature to be driven under load. No, combustion probably won't be as complete, but neither would it be at idle. Oil pressure is higher than at idle as well. All in all, I think a cold engine under load will be getting just as much lubrication as a cold engine at idle. If it's lubed, I don't see how it's getting damaged.

I think we tend to think of temperature variations in human terms, whereas machinery is less affected by them.

 

Okay so when its -30 outside your engine block is at -30 also. Starting it up and driving it is going to shock warm that engine. I think it should be done gradually. Which is a good idle speed.

Isn't an engine more efficient when its at normal engine temperature? Driving it while its cold its not going to run the same as it is when its warm. At least with my truck I notice a lot of difference. I'm starting to think its overall minimal damage if any by driving it once in a while at extreme temps.

 

That's what I mean; metal that melts at 2400 degrees gives less of a crap about the difference between -30 and 70 than we do. And "shock warm" sounds scary, but what does that mean to an engine? Not much, I'd say.

"Isn't an engine more efficient when its at normal engine temperature? Driving it while its cold its not going to run the same as it is when its warm".

Sure. But do I really care if it's idling inefficiently, or driving inefficiently? Not really.

"I'm starting to think its overall minimal damage if any by driving it once in a while at extreme temps".

Not exactly sure what you mean here, but I think I agree.

Hey, I'm always open to a sound, scientific argument. If someone can tell me exactly what harm is caused by (gently) operating an engine that isn't fully warmed up, I'm all ears.

 

This isn't scientific, but this is the way i look at it. I don't like cold, I like a warm ride to work. Believing that it is good for the drive train if it is warmed up makes me feel less guilty for burning more fuel

 

I like being warm as much as the next guy, but I don't think that's good for the drive train - well, the engine, since none of the rest of the drivetrain gets warmed up until you start driving.

"The best thing to do is to turn the engine on and imme­di­ately start dri­ving it lightly. That way you are warming up the engine to it’s opti­mal tem­per­a­ture as fast as pos­si­ble. Your car's engine oper­ates most effi­ciently when it’s run­ning at a cer­tain tem­per­a­ture range; the faster the engine reaches that tem­per­a­ture, the bet­ter. Until the car is warmed up, the engine is wear­ing out much faster than nor­mal because the engine oil pro­vides the best pro­tec­tion against fric­tion between all the mov­ing metal parts when it’s it’s com­pletely warmed up. Until it reaches that state, the engine is wear­ing out much faster than nor­mal. Turn­ing the engine on and imme­di­ately dri­ving lightly warms the car up much faster than idling.

http://antranik.org/the-myth-of-warming-up-your-engine/

I totally agree with this. If you let the engine idle to warm up, it'll take twice as long to start running optimally as it does if you start driving as soon as the oil is pumping. Keep your foot out of the gas tank while you're driving it cold, and I think your engine will be a lot better off in the long run.

 

My machinists have always warned me of the dangers of running my race bikes hard when cold. I've always heeded the warning but had a buddy one time who figured he knew more than the machinists and proved the theory for us all to see. A cold seized engine is not a fun way to end a day. but on a two stroke single cylinder bike not to hard or expensive to fix. I doubt the failures will be as spectacular or immediate on our relatively detuned and ruggedized trucks but the concept that parts should have thermally settled into their designed running dimensions/temps before they can be run at spec or risk excess wear to achive maximum longevity and performance seems valid to me. I'm sure that since these are general purpose consumer level vehicles designed to put up with the abuse and neglect of non professional operators there is a larger margin of tolerance but I can't see that romping on a cold engine seems like a good idea. I recently, within tha last couple years, had to replace one of these engines and can tell you it is no where near as simple or cheap to rebuild one of these engines as the bikes were.

 

I did not think anybody would bring up a cold seize or four corner seizer. I have done this one or two times with some of my sleds and have fixed more other people sleds than I can count. Not fun or cheap to fix. Def more 2 stroke related.

Marine related link
http://www.groupk.com/tec-seizures.htm