Warming vehicle in cold harms engine
By Jay Bennett, Popular Mechanics
In the thick of winter, the common wisdom is that when you are gearing up to take your truck out in the cold and snow, you should step outside, start up your engine, and let it idle to warm up. But contrary to popular belief, this does not prolong the life of your engine; in fact, it decreases it by stripping oil away from the engine’s cylinders and pistons.
In a nutshell, an internal combustion engine works by using pistons to compress a mixture of air and vaporized fuel within a cylinder. The compressed mixture is then ignited to create a combustion event—a little controlled explosion that powers the engine.
When your engine is cold, the gasoline is less likely to evaporate and create the correct ratio of air and vaporized fuel for combustion. Engines with electronic fuel injection have sensors that compensate for the cold by pumping more gasoline into the mixture. The engine continues to run rich in this way until it heats up to about 40 degrees Fahrenheit.