So this is a simple question, one of our big pumps we use in irrigation frost protection is an older engine so it runs a bit rough and smokes a bit on startup but this only last like 2 mins and then it runs fine. This is also somthing that happens only when it's cold as well obviously. Past 3-4 nights I started it around 2am, cold night near frost and it smoked a bit then was fine as usual. Tonight was different, it's the coldest of the nights yet and when I went to start it up the engine started up like it was already warmed up and had just been running, even though it was stone cold. Obviously this isn't like a what's wrong with my engine kind of thing as the engine is fine it's more just curious of what would be different to make it start like it's warm when it's not? Engines are interesting so I am curious of such things and yes it's a diesel.