Team O'Neil weighs in on the "car-warming" debate

"Dusty Ventures" (dustyventures) 01/25/2016 at 13:17 • Filed to: None

9

33

Please, warm your car up in the winter, despite what you may have recently heard in the press. Here’s why.

Metals expand and contract at different rates, based on temperature. Aluminum, for example, contracts about twice as much as steel at low temperatures. This means that crucial tolerances, like those between your crankshaft and bearings, can be VERY tight at low temps. Does your car turn over slowly in the winter even with thin oil? It’s because your engine is basically almost seized as some parts have contracted more than others.

You probably also have aluminum pistons in steel cylinders, which expand and contract at very different rates. At cold temps, your aluminum piston will contract more than the steel cylinder, creating a larger than normal gap between your pistons and cylinder walls. Do a compression test on a cold engine and you’ll see what we’re talking about.

What’s worse is that your pistons will expand much quicker than your cylinder walls and block, because the pistons are small and light, and the block is big and heavy. This means that your pistons will be at full size, and the cylinders that they travel in will be smaller than normal. There is a window of time when your pistons are warm but your block is still cold, and revving or putting load on your engine while it has these extra-tight piston clearances isn’t good for anything.

Your engine block, heads, crankshaft, cylinders, pistons, piston rings, camshafts, valves, bearings, etc are all made of different metals that are effected very differently by heat and cold. It was designed with a reasonable operating temperature range in mind, and we as drivers need to respect that and avoid driving outside this temperature range whenever possible.

!!!error: Indecipherable SUB-paragraph formatting!!!

CalzoneGolem > Dusty Ventures 01/25/2016 at 13:22

24

Do I have to warm up my car if I have snow tires?

MasterMario - Keeper of the V8s > Dusty Ventures 01/25/2016 at 13:23

0

I’ve never really thought of it from that perspective, but it makes complete sense.

450X_FTW > CalzoneGolem 01/25/2016 at 13:24

4

Not if you check them with a digital gauge

DrJohannVegas > CalzoneGolem 01/25/2016 at 13:24

5

If you have snow tires, your engine will work fine in the vacuum of space. Even from cold start...

(Also, rich Corinthian leather.)

CalzoneGolem > DrJohannVegas 01/25/2016 at 13:27

0

Obligatory:

Rico > Dusty Ventures 01/25/2016 at 13:27

0

Makes total sense. What I do is once I start the car I watch the revs, at the start it’ll idle a bit higher than after about 60 seconds or so you can hear and see the revs come down to a more normal idle. Once that happens I back out of the driveway and leave going at a slow but stead speed never really getting higher than 2k-2.5k rpm by the time I’ve been driving for 5-10 mins this way the car is almost at operating temp.

On exceptionally cold days I will start the car, start the seat warmer for about 5 mins before I get in and leave, in 5 mins the seat is already relatively warm and I can start driving away.

CalzoneGolem > 450X_FTW 01/25/2016 at 13:28

2

I checked with digital gauge and he said it was ok.

Justin Hughes > Dusty Ventures 01/25/2016 at 13:28

1

DrJohannVegas > CalzoneGolem 01/25/2016 at 13:30

0

Optional (and perhaps ill-advised):

Eff the alternate timeline.

DrScientist > Dusty Ventures 01/25/2016 at 13:31

1

i dont disagree with their recommendations, but would these guys know more about my engine than the guys who designed the engine?

MontegoMan562 is a Capri RS Owner > CalzoneGolem 01/25/2016 at 13:31

0

But who calibrated the digital gauge? And they damn well better have used a digital gauge to calibrate it...

CalzoneGolem > DrJohannVegas 01/25/2016 at 13:32

0

I think that guy has his jacket on backwards.

MontegoMan562 is a Capri RS Owner > Dusty Ventures 01/25/2016 at 13:32

5

Couldn’t care less about all of it, I just want a warm interior of the car

Urambo Tauro > Dusty Ventures 01/25/2016 at 13:33

3

I totally understand both sides of the debate.

They both make sense. Either you take a risk by putting a load on the engine while it’s still cold, or you take a risk by having the engine spend much more time below operating temp while idling.

Master Cylinder > Dusty Ventures 01/25/2016 at 13:34

1

My car’s engine has aluminum pistons riding in aluminum bores. Therefore I warm up my car by flooring it immediately and banging off the rev limiter for 3-5 minutes until it comes up to temp.

CalzoneGolem > MontegoMan562 is a Capri RS Owner 01/25/2016 at 13:35

0

Daily Drives a Dragon - One Last Lap > Dusty Ventures 01/25/2016 at 13:35

1

So as soon as I crank it, I should immediately bash the limiter?

Urambo Tauro > Urambo Tauro 01/25/2016 at 13:36

3

I usually go ahead and drive it to get it up to temp more quickly, but until that happens I’ll minimize the load on the engine by keeping the revs low.

Master Cylinder > Master Cylinder 01/25/2016 at 13:37

1

In all seriousness though, this is good advice in the article. I would modify it slightly to clarify that “warming up” the car doesn’t have to mean idling it in your driveway. Low-load driving (don’t lug the engine, don’t rev it high) is generally the recommended way to bring an engine up to operating temp. Most cars idle hella rich and all that fuel washing the cylinder walls ain’t good for the motor either.

Steve in Manhattan > Dusty Ventures 01/25/2016 at 13:37

0

Tom & Ray said that, in weather other than the coldest, warming it up for 10 seconds or so is sufficient. Any damage that occurs happens in that second or two before the oil resting in the pan gets up into the engine to do its job.

Highlander-Datsuns are Forever > CalzoneGolem 01/25/2016 at 13:45

0

Depends on if they are Nitrogen filled. If filled with nitrogen (argon also works) you do not need to warm up your car.

CalzoneGolem > Highlander-Datsuns are Forever 01/25/2016 at 13:47

1

I used Freon because that’s what I put in may air conditioner and that makes things cold just like snow.

Highlander-Datsuns are Forever > CalzoneGolem 01/25/2016 at 13:54

1

Good call!

Manwich - now Keto-Friendly > Dusty Ventures 01/25/2016 at 14:12

0

For me, on a really cold morning, I’ll let it run for 5-10 seconds and then reverse out the driveway.

By the time I’m out of the driveway, 30 seconds has gone by.

And then I take it easy until I get to the highway. By that time, at least 5 minutes has gone by.

The key is to not put the engine under heavy load while cold.

And I’ve never had an engine die on me as a result. Usually rust kills my cars long before the engine dies.

MontegoMan562 is a Capri RS Owner > CalzoneGolem 01/25/2016 at 14:36

1

This logic is good logic

MontegoMan562 is a Capri RS Owner > CalzoneGolem 01/25/2016 at 14:36

1

well played sir

CalzoneGolem > MontegoMan562 is a Capri RS Owner 01/25/2016 at 14:43

1

From the drawer of Jeremy.

CalzoneGolem > MontegoMan562 is a Capri RS Owner 01/25/2016 at 14:43

1

I did the math.

Klaus Schmoll > Urambo Tauro 01/25/2016 at 14:48

1

Exactly what I do. Nice to meet someone who understands the concept of not prolonging the cold start period.

gin-san - shitpost specialist > CalzoneGolem 01/25/2016 at 15:01

0

Only if it’s FWD. If it’s AWD, brown, and diesel, don’t worry about it.

A quick check of the dipstick to see your tire fluid is topped up may be a good idea, though. If your tire fluid is frozen, you may need to warm up the car a bit.

Source: I am very obviously a mechanic, no follow-up questions please.

CalzoneGolem > gin-san - shitpost specialist 01/25/2016 at 15:05

0

*writes our shopping list containing the item “tire fluid” in a variety of fonts*

Battery Tender Unnecessary > Dusty Ventures 01/25/2016 at 15:17

3

Dusty Ventures > Justin Hughes 01/25/2016 at 15:26

1