1. If an engine is warm and I start it again, it that consider a Cold Start?

2. If an engine is cold, and I'm starting it for the first time, is that a Cold Start?

3. Does weather play in part in the definition of Cold Start? Meaning, it could be 115 degrees in AZ and I'm starting the car for the first time. Or I'm starting up an engine that has been driven, and the outside temp is 2 degrees in MN.

 

I would say it's the first time you start an engine after it has sat for a certain amount of time (8 hours maybe?)

 

I think cold start would be any engine start when the engine oil temperature isn't near operating temperature, say below 150°F. I know my Integra Helms defines the engine being cold as when the engine head is below 100°F (for valve lash adjustments and such).

So yes, any engine start when the engine hasn't been run for several hours, no matter what the outside ambient temp, would be considered cold start, and is when most engine wear occurs because the oil is too thick at cold start to properly lubricate everything in the engine.

This is why I recommend 0w30 or 0w20 oil (depending on what operating viscosity your engine requires).

Curious, why not post this in the Tech/Misc forum?

 

Didn't think about that.

 

Below a set ECT, usually 100* iirc

 

If it kicks into high idle for more than a couple of seconds after startup it's a cold start.

 

i would say if your oil and coolant are the same as outside air temp its a cold start up.