There is always the reason that letting a cold engine idle in cold weather is one of the worst thing you can do to a motor. Condensation will form water and acids that dilute the oil, add more gunk to the intake and rot the exhaust system. Plus none of the non-motor moving parts are being warmed up.
Ill say it again...There is nothing wrong with leaving a car running unattended.
Buy letting a cold engine idle in cold weather you are, and will over a matter of a few minutes (given that the t-stat and cooling system are in correct operational condition) warm up the engine to its optimum operating temp. So for a matter of minutes (while the engine is heating up) yes, you will be producing access water, which exits the vehicle through the exhaust system. Once the vehicle has reached normal operating temperature most of the residual water in the exhaust will evaporate, as hotter, better burned exhaust gases flow through the system. The % of these minor acids and water that actually dilute the oil is extremely minimal. The lubrication system should not be affected by any measurable amount. You must also keep in mind that our SHOs have an extremely efficient combustion process (as do most newer distributorless vehicles) the pent-roof combustion chamber design also aids in very efficient overall burn in dynamic temperatures and conditions.
The BENIFITS of leaving your vehicle running and letting it warm up FAR outweigh the bad. Oil gets thicker when it’s cold (and hence less lubrication). Letting an engine warm up provides time for this oil to also warm up and provide better lubrication, all while the engine is under no load whatsoever, simply idling...the least amount of running stress. SHOZ123, would you rather prefer letting your oil warm up while you climb through the rpm range and work through the gears, applying much greater stress and pressure on an engine with cold oil that is not lubricating to its fullest extent? I sure wouldnt...
Next if you have an MTX SHO, your gearbox will eventually get heat soak from the motor and heat up pretty good. Again, the lubrication here also works better when it’s warmer, providing easier shifts and prolonging gearbox life. That’s all I can think of right now, but I will continue to leave my car idling in the mooring. Speaking from experience, as Saranac Lake is one of the coldest places in the entire USA throughout the winter (just look on the national news sometime), I can honestly say your car will love more if let her warm up in cold weather. If you are in check with your car and maintain it, you should have no problem with letting it run. If you do, your paraniod. finger
SHOZ123,
Why is that almost every time i see a tractor trailer or deisel truck; whether it be at a rest stop or simply sitting in a parking lot, its idling? Why do they run their engines long into the night? Do they like to waste fuel? Why do the school buses idle for periods of 1-2 hours while stationary? Is it all for fun? shrug
please, "enlighten" me wink