Your engine is going to reach operating temperature a lot quicker if you drive it rather than let it idle. It simply comes down to how much load is on the engine. Load creates heat. A engine is designed to work. Sure the ECU raises the idle speed for a number of reason, the main one is so the CAT reaches light-up temperature faster so it will function. The majority of engine wear occurs around the first 3-6 minutes of operation.
I have strip a couple of gasoline engines over the years where the thermostate has been removed. These engines are usually show very high piston and bore wear because of over cooling, quire often very uneven bore wear between the cylinders.
I have strip a couple of gasoline engines over the years where the thermostate has been removed. These engines are usually show very high piston and bore wear because of over cooling, quire often very uneven bore wear between the cylinders.
Since we are focusing on wear in the first few minutes of a cold start, I'd just like to add that a cold engine is typically a dry one. There has been plenty of time for the oil to drain into the oil pan. Oils typically have a different viscosity between cold and warm temperatures and their peak effectiveness is while warm.
Additionally loads at higher revs on a cold engine are more likely to cause additional wear than merely idling. The car warms up faster but during the time it is least optimally lubricated if it is driven while cold. Idling a car provides the least amount of load and stress on an engine. All things equal, it can not cause more wear than actually driving it, no matter how careful you are...again, if you are careful though the difference is fairly negligible. There is only a benefit to fuel economy (and emissions) if you choose to drive instead of idle.
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