warming up your car..., its a bad thing Options

[macavely]

Ok I over heard some guys talking about how they have to warm up their cars. There isn't many things i know, but one thing i do know for sure is, warming up a car is a bad thing. Car engine belive me or not were never made to sit idle.

[SpedToe169]

You're correct that it's not good to idle a gas engine for a long time, but 5-30 min to warm it up is totally reasonable. I wouldn't leave one idling overnight like you would/could with a diesel. Warming up isn't critical in most stock engines because they're made to be abused and driven before they're warmed up properly. An engine should be warmed up for a number of reasons. First off the oil viscosity changes very rapidly as the oil heats up from ambient to about 170deg. During this time oil flow is not as it was designed from the factory as it is many times more thick. Secondly, the clearances in an engine are very tight. As the motor heats up it undergoes thermoal expansion of all its parts. Different materials expand at different rates with changing temp. Engine builders know this and design engines so that the tolerances are optimal at operating temperature. Running an engine too hard while its too cold can damage it due to metal to metal contact and improper oil flow. It's always good to let your engine warm up for a couple minutes before taking off, but its usually not necessary on todays automobiles. Race motors are the exception. Running a race motor hard without FULLY warming it up (oil temp around 220-240) WILL almost certanly destroy it.

Sorry for the novel, just wanted to clarify.