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Originally Posted by realchef
Sorry, but stating that an engine will not warm up by idling is absolute nonsense. Yes, putting load on the engine will cycle it quicker, but it will also increase the damage from the added stress of the cold metal.
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It isn't nonsense at all. At normal ambients, no problem. Idling isn't good for it, but it won't hurt it much. At -25 to -40, which is what we were discussing, many engines won't warm up, ever. That is why we use winter fronts, and other devices, to keep the heat in.
Many studies (SAE, manufacturer's, and others) have shown that cold engine wear on start up is closely correlated to the duration of the warm-up cycle. It has far less to do with load on the engine (assuming you aren't lugging it, everything within reason). Wear does correlate with high engine rpms during this warm-up cycle. Putting load on the engine is beneficial, not harmful. You don't need to worry about fatigue stress, you need to worry about boundary layer lubrication and the relative fit of the parts. You can use a thinner oil to improve lubrication and pumpability. You can't change the issue of the fit of the parts. What you can do, above all else, is reduce the duration of the warm-up cycle.
BMW know this. That is why they tell you not to idle the engine to warm it up, same as all the other manufacturers.
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Originally Posted by realchef
I wonder if the people stating drive away cold have ever lived in a freezing environment. It is just not an option at times. Your breath's condensation can freeze and glaze the inside of a windshield. Thinking that when leaving work at 5 pm on a 15* day, you can start and go is not realistic.
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Yes, lived there. See my posts above. Does north of the 60th parallel count? I also acknowledged that it isn't an option at times. Safety first.
