GREENSBORO, NC – It's a debate that happens every winter. Should you start the car to warm it up when the temperature drops below 40 degrees?
When WFMY News 2's Hope Ford posted question in December 2016, the reactions on the topic were mixed.
Some wrote they warmed their cars up because, well, who likes getting in a cold car? Some said they were too impatient to wait for the car to warm up.
But others gave theories on why it was important for the health of the car.
“Warming up your vehicle will make it last longer.”
“I would so you don’t crack your block.”
“Keep the gas tank full so the fuel line won’t freeze up.”
Then, there were the people who were avidly against the practice.
“No, there is no need for that anymore with the current technology of cars.”
She took the question to Cynthia Roy, a 15-year ASE certified mechanic and owner of Roy’s Automotive in Greensboro. She also asked an expert with Cars.com, Joe Wiesenfelder.
Ford: Does warming up the car make it last longer?
Roy: No, it actually does the opposite. You can actually decrease the like span of your vehicle if you let it idle too long.
Wiesenfelder: The engine must reach its optimal operating temperature before revving the engine too high. If you start the car and stand on the gas right away, it can increase wear, especially if the oil hasn’t warmed up and begun to flow freely.
Ford: Will your engine block crack if you don’t warm up the car?
Roy: No. In very cold climates, if you’re in Alaska or Northern Canada or Antarctica, it’s probably a good idea to warm up your car.
Wiesenfelder: Not unless your car has other underlying problems.
Ford: Does keeping the gas tank full keep it from freezing up?
Wiesenfelder: It isn’t a bad idea because the more air there is in the tank, the more moisture can form. Moisture is what leads to frozen fuel lines. Gasoline antifreeze can combat this – though it bears noting that alcohol is now pervasive in U.S. gasoline (typically 10% ethanol), and it absorbs moisture and allows it to be burned off. Only when gas gets too old does it become more of a problem.
Ford: Does letting the car idle make it drive better?
Roy: Your car which actually warm up slower if you let it idle too long. If it doesn’t warm up quickly, then yes, the car will run bad.
Wiesenfelder: The biggest difference I still notice in winter is how some automatic transmissions behave when cold. They may be jerkier or shift harder, but running the engine doesn’t necessarily warm up the transmission. Driving the car does. Once it gets going, it starts to behave normally.
Ford: Are there advantages for older cars versus newer cars?
Roy: Yes, cars that have carburetors , not fuel injection systems, should be armed up. You should probably warm that car up for above five minutes. Newer vehicles, I would warm it up for really only 30 seconds, just enough for the defroster to kick on and clear the windshields so it’s safe to drive.
Wiesenfelder: Driving a car warms it faster than letting it sit. practically all new vehicles in the mid-1990s, that’s just a memory for most of us. Young drivers don’t know what a “cold start” is or what it means to set the choke.
Ford: Does it waste gas to warm up or idle the car? What about pollution?
Roy: Yes, it does, because the car is going to run colder and therefore it’s going to run richer and all that fuel is going to bypass the piston rings and go from the combustion cylinder into your engine and mix with your oil and then it’ll thin the oil out. And you have raw gas going out the tailpipe.
So, looks like it's an old wives’ tale. The car will warm up, heat wise, if you let it idle for a long period of time, but there are risks to idling the car. Driving a car will warm it up faster.
Oh, and as one person noted in the Facebook comments, it’s easier to get a car stolen if you let it idle.
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