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Warming up your car - kinder to the engine?

Dear Tom and Ray,

My husband has always insisted that warming up a car a few minutes (after is sat a few hours, or overnight) before driving off is better for the car, presumably because the different metal parts in the engine can heat up and expand at the same rate. In today’s (1/24/2010) NW Autos section of the Seattle Times you answered a question from a valet at a country club in Wisconsin. He was concerned if he might be HARMING the members’ cars if he warms them up for them, and in your response you mostly focused on the wasted gas and harm of the environment - I’d like to know if you can harm a car by NOT warming up!

Thanks, Chris

Tom and Ray don’t answer questions here, but we do. A short warmup does no harm, but over a few minutes does no good. In Anchorage I would let the car run for about 30 seconds, then drive (gently) off.

Start the engine, put on your seat belt, adjust your mirrors and the volume of the radio and drive. Normal driving after that should not harm your engine.

“Atomic batteries to power, turbines to speed.”

I drive an over 30 year old diesel; in the winter time I let it warm up for a minute or two and then drive it gently until it’s up to operating temperature. I would think newer cars have improved enough to not really need to warm up, however I imagine it’s better for older cars to warm up the oil and the valves for a very short time before driving…

I’ve always heard warming up in super cold is a good idea but it only needs a few minutes. If u can’t warm up keep it under 2,000 rpm til it has a chance to warm up a little.

The main reason to warm up an engine is that cold oil doesn’t flow very quickly and doesn’t lubricate as well. In carbureted vehicles, you usually had to keep your foot on the gas for at least a few seconds before it would keep running in cold weather. I believe that had to do with the temperature in the combustion chamber being too low and needing to run rich for a few seconds. That isn’t an issue anymore, so all you’re left with is lubrication. That starts to be an issue at like -20F or so. Or it did in the 90s…current oils may be better. You shouldn’t have any metallurgical problems until it’s too cold to start the car at all. Seals between metal parts, though, can be damaged by rapid temperature changes…like you get when you don’t warm the car up (or when you don’t plug it in or keep it in a heated garage when it’s extremely cold). At best you get oil leaks, at worst you ruin your head gasket. It isn’t ever going to be cold enough in Wisconsin to do any worse than that.

So yeah, you can accelerate wear and tear by not warming the car up.

It may be safe to go sooner, but you always know you’re good to go when your heat vents start blowing warm.

Oh, and if you’re above about freezing and you’re driving a fuel injected car (anything after about 1993, most cars after the late 80s) there is absolutely no reason to worry about warming the car up.

The OP wrote:

He was concerned if he might be HARMING the members’ cars if he warms them up for them,

I agree with all the replies thus far. However, with today’s fuel injected cars, you will do no harm if you let the car warm up. If warming up the car is needed for defrosting the windows or for your comfort, then do it.

Engines wear most when they are below operating temperature.Warming a car up takes much longer at idle than driving the car. When you are starting a car in cold temps you are washing the cylinder walls with gasoline, I have seen cars that were idled a lot and driven on short trips in our cold climate gain a quart over full on the dipstick which means that you have a quart or more of gasoline in your crankcase. Start your car and in 30 seconds drive gently for the the first few minutes. If being cold REALLY bothers you get a remote start and let it warm up as long as you want, it’s only a car.

Warming the engine for a few minutes then driving it gently, at least until the temp gauge begins to register is what I do when temps are very cold outside. In addition to the engine, there’s the transmission and power steering to consider. A little warming and letting the hydraulic fluids flow and thin a little is better in my opinion than immediately tromping on the gas. I definitely wouldn’t just turn the key when it’s 5 degrees outside, put it in gear and floor it.

Warming up a car excessively is unnecessary, but won’t hurt it—cop cars and taxis spend all day pretty much every day idling without harm.

You don’t tell us how cold.

Best bet IMO is to start the car, do the adjustments ms suggested and then drive off as soon as the engine will provide basic power. Drive easy for a mile or so while the engine and other parts warm up to operating temperature.

Many people fail to consider that there are parts other than the engine that need to warm up. They include the transmission, and suspension systems. They don’t warm up with the engine. Idling when cold is hard on an engine. It is better for the engine to be driven as soon as it will reliably power the car.