Stop hurting your engine by 'warming up' the car when it's cold out

(frankieleon on Flickr)

Harsh driving conditions in winter are already hard on your car, but you could be making things a lot worse if you’re turning your vehicle on in the morning so it can “warm up” before you drive off.

If you’re one of the many drivers who thinks it’s important to idle your car — turn it on and let it sit — in these frigid winter months to protect the engine, you’ve likely fallen victim to a myth that may be doing more harm than good.

We spoke with mechanical engineer and former drag-racer Stephen Ciatti about the pervasive myth that you need to warm up your car in the winter.

For the last 26 years, Ciatti has worked on combustion engines — engines that generate power from burning fuel, like gasoline — and currently oversees all of the combustion engine work at Argonne National Laboratory in Illinois.

To get straight to the point, Ciatti said that idling your car in the cold not only wastes fuel, but it’s also stripping oil from critical components that help your engine run, namely the cylinders and pistons.

How it works

Under normal conditions, your car engine runs on a mixture of air and vaporized fuel, gasoline in this case. When that mixture enters a cylinder, a piston compresses it, which — at the risk of oversimplifying — generates a combustion event, powering the engine.

But when it’s cold outside, gasoline is less likely to evaporate. Your car compensates for this initially by adding more gasoline to the air-vapor mixture — what Ciatti calls running “rich” — and that’s where the problem begins. Here’s an animation that shows how pistons drive the cylinders in your car to generate a combustion event:

“That’s a problem because you’re actually putting extra fuel into the combustion chamber to make it burn and some of it can get onto the cylinder walls,” Ciatti said. “Gasoline is an outstanding solvent and it can actually wash oil off the walls if you run it in those cold idle conditions for an extended period of time.”

Over time, that washing action can “have a detrimental effect on the lubrication and life of things like piston rings and cylinder liners,” which are critical to running the cylinders and pistons that breathe life into your engine, Ciatti said.

The bottom line: Contrary to popular belief, idling your car does not prolong the life of your engine, rather it shortens it.

A simple solution

(REUTERS/Arben Celi)

Thankfully, your car doesn’t run rich the entire winter. It only happens when the gasoline is cold. Once your engine warms up to about 40 degrees Fahrenheit, the car transfers to normal fuel consumption rates.

So you might think by idling your car, you’re warming it up, which will prevent this problem. But don’t confuse warm air coming from your car’s radiator with a warm engine. Idling is, in fact, the root of the problem.

“Idling isn’t really getting the engine up to temperature, and until that happens the little brain box on the engine is going to keep sending rich fuel mixture to the cylinders so that it can ensure that enough is evaporated for a consistent combustion event.”

The fastest way to warm your engine up is to use it, aka drive!

Some might tell you that the power steering fluid — the oil that pushes on pumps enabling you to control the car’s wheels — might be too cold to flow properly. To that, Ciatti said no way.