Warming up engine is useless and waste gas

[B320i]

Given my experience with my BMW - I'd be inclined to let it warm up for a half-minute to a minute in cooler conditions for a couple of reasons:

- Shifting the gearbox, even in "cool conditions" (between 50-65ºF, 10-18ºC) starting out can be notchy. With fast-moving traffic, you need to keep up, shift quickly and get moving.
Idling in neutral would seemingly allow fluid to be splashed around and helps the initial shifts quite significantly.

- Engine response when cold is delayed and exasperated:
E.g., Starting off is fine, but when you go to shift, the RPM is sort of "hangs" and drops slowly. Slowing down, there is a delay before the engine starts to slow down, and it is usually a slight "jerk" that accompanies.
In other words, it just feels "weird" until the temperature gauge gets out of the blue area and the engine comes out of the cold-start regime.

 

[Pontual]

Originally Posted By: Quattro Pete
Originally Posted By: camrydriver111
Do aircraft pilots warm up their engines, or do they just turn them on and fly away? I believe the same principles apply and for the optimum performance and safety I warm up my engine.

The difference is that you have to put the aircraft engines at full power to take off, so they need to be up to operating temp.

You do not need full power to start driving your car. The point is to start driving (moderately) ASAP, as that way the car will warm up faster.

Pilots do give very little warmup, but they have taxi out, from the ramp to the runnup area (near the runway hold short lane), then do 2 magnet checks and 2 or 3 propeller cycle checks at medium rpms (1700 to 2k rpms), so it gets pretty warm for takeoff.

 

[Pontual]

Originally Posted By: Shannow
Let your aircooled engine warm up then...to the point that the oil temperatures are in the "normal range" (note, there's nothing in Lycoming recommendation to specify what the "range is"), check that your prop hydraulics function properly, and have at it.

The green arc in the gauge is the normal range. From about 70 to 245 F.

 

[robertcope]

I start the car. By the time I get the top down, seatbelt on, etc, it's time to go. Gently until it's good and warm. I believe Honda says five minutes before you full throttle somewhere in the S2000 manual. Maybe I am making that up.

robert

 

[Shannow]

Originally Posted By: Pontual
The green arc in the gauge is the normal range. From about 70 to 245 F.


Thanks,
so "normal" for moving off/prop checking purposes is a minimum of approximately room temperature...

 

[Garak]

Originally Posted By: Pontual
Pilots do give very little warmup....

In my limited flight training experience years back, that was my experience, too. The instructor would sometimes have you warm things up a little in the cold, but no "attempts" to get to operating temperature. You'd freeze to death in a Cessna waiting for that in -30 C.

In Regina, it would be a short warmup. Checklists, taxi clearance, and not much more than that, since there isn't usually a significant amount of traffic to wait for. The lift you experience at -30 and colder is pretty darned impressive, too.

 

[crazyoildude]

I always warm my engines up especially when it gets below 20 degrees out i let them warm 5-6 minutes if it gets down to 0 i give it 8-10 minutes then drive slowly until the trans warms up.. Never a problem..

 

[Stewie]

Originally Posted By: Quattro Pete
Originally Posted By: Stewie
I personally wait around 1 min until my windshield defrosted

If your windshield is frozen, 1 minute of idling is not going to fix it, me thinks.


It does for me.

I got Rain X in my reservoir and outside air in full blast.

 

[Yup]

Warming up a car is COMPLETELY useless. With that, there are a couple of scenarios where it makes some sense. I spent much of my life in northern MN so extreme cold isn't 0 degrees. It's -35F. In those situations, your best bet is to get in and drive ASAP because your engine warms faster when being driven. However great in theory, in reality, in extreme cold you'll most likely need to let it idle because it won't go into gear or the clutch fluid will be so thick the clutch won't engage or the tranny fluid is so thick it'll shift weird if at all or the moisture from breathing will fog all your windows or you're just lazy and want a warm car because you only live once and you're not going to set your butt into a frozen seat for the next 30 minutes because you're not stupid. And that, my friends, is how to write a run on sentence of reasons you'll let your car idle but, really, just going as soon as your car is able is the best bet.

 

[Yup]

Originally Posted By: crazyoildude
I always warm my engines up especially when it gets below 20 degrees out i let them warm 5-6 minutes if it gets down to 0 i give it 8-10 minutes then drive slowly until the trans warms up.. Never a problem..


Below 20? LOL Jesus, that's a heat wave in MN. Anything above -10F I get in and go unless I'm having window fogging issues. Just drive easy. Below -10 windows need de fogging usually and tranny does weird things unless I warm it. If your car moves and doesn't act disturbingly weird (like serious issue like not shifting), not necessary to warm.

 

[xfactor9]

Originally Posted By: camrydriver111
My car is not very responsive if I don't warm it up. Acceleration and transmission shifting is very sluggish.

I do not like to drive a car that isn't warmed up.

From my own personal observations I can tell the article is not true.

Do aircraft pilots warm up their engines, or do they just turn them on and fly away? I believe the same principles apply and for the optimum performance and safety I warm up my engine.


Pilots do warm up their engines by virtual of having to do their checklist, taxiing slowly to the runway, then possibly wait for clearance. It takes 10+ minutes to do this, and by then the engine is warmed up. Piloting a plane is so different than driving a car; you can't just walk into your garage, start it up and immediately drive away. This is why I laugh when I hear about how flying cars will be available soon.

 

[Dyusik]

hths was an idiotic statement commonly found with half thinking ( its ht and hs, and many people address ht not hs), my common sense is if you were to slide an object against another, and will show a dust trail. Slide it under load and it will scrape.
My IS sound horrid without warmbup, same with the chev, a minute or two an all is well ( longer for the lexus)
I alway welcome corrections, I'm here to learn.

Originally Posted By: Shannow
Originally Posted By: Dyusik
Ep additives work dead cold and wear is the same under load as it is at idle, hths is fine at 1.0.
No thanks, I'll stick to common sense.


What are you exactly saying here...
a) what is a "common sense" approach ?
b) how do you get an HTHS of 1.0 ?
c) which is better, slightly higher load to speed up warmup, or idling it for an half hour to get everything hot before driving ?


Macwest is just trolling, so no point getting him to explain his position.

 

[Shannow]

Dyusik,

re "shear", that's what happens to a lubricant that's caught between two moving surfaces...the oil next to one surface moves at the same speed as the surface, the lubricant adjacent to the other surface moves at the same speed as THAT surface. The lubricant between them moves at a different speed.

Take a skim board moving at 100fps (it's a number, not reality). It's moving at 100fps, the thin film of water next to it is 100fps, the sand, and the thin film next to it is 0fps...exactly half way between them the water is moving at 50fps, and there is a gradient between them.

That's shear, not like some think a cutting action.

"shear rate" is the speed difference between surfaces, and the gap between them...100fps, with a 1' gap gives a shear rate of 100.

Bearings move much, much faster...a 2" journal spinning at 3,000 RPM (50 RPS) has a surface speed of nearly 14 fps (157"ps). If the radial clearance (half the bearing clearance) is 0.001" (typical)...gives a shear rate of 157,000.

The bearing doesn't run in the centre, it's pressed to the side (like the skim board, the rider's weight pushes it to one side), and the gap is closed at the minimum point, to tenths and hundredths of thousands of an inch.

The "shear rate" is thus much, much higher than a simple calculation of surface speed/radial clearance.

Here's some typical shear rates in engine components

At about 100,000 is when the VII polymers get stretched, it is called "high shear"... HTHS is high temperature (150C is not abnormal in bearings, where the metric matters), High shear (when the shear rate is above 1,000,000.

The same thing happens at low temperature high shear, the lubricant thins out under high shear.

So at 40C, the multigrade in question dropped from 55ish to 45ish cst due to the shear rate...drops about the same percentage at 100C, and at 150C.

At the extreme cold temperature, the correlation is the CCS figure, the cold cranking simulator is similarly a high shear rate measurement, but about 100 times as thick as the 40C number.

Cold thick oil in the right places gives high hydrodynamic film thicknesses.

 

[KrisZ]

Originally Posted By: Shannow
Cold thick oil in the right places gives high hydrodynamic film thicknesses.


Yup

But the majority seem to think that it's all metal on metal action during a cold start.

 

[gathermewool]

Originally Posted By: HerrStig
Originally Posted By: gathermewool
Originally Posted By: Garak
Originally Posted By: Stewie
What do you guys think?

That was clearly written one year before Ontario's latest cold snap. If he wants to dress up like a snowmobiler and drive off in 30 seconds in -40, all the while avoiding breathing in his interior until the engine gets some heat into it, all the power to him.





I've never experienced -40F/C temps, so take this with a grains of salt: I typically dress for the weather, which means that driving all cozy in a car in my winter coat, beanie, scarf and gloves is a lot less daunting than being out in the actual elements. I have no problem hopping in and driving off, so long as the air is dry enough to literally absorb all of the moisture in my breath before it even reaches the windshield.

I try to be nice to my vehicles and typically don't even use the heat if it's above freezing, because I don't feel I need it, but the thing is a machine, so if it's -15F, I'll immediately crank the defrost to high after a mile or two, both to put some more load on the engine, but to also put whatever heat the coolant has absorbed into the cabin, as quickly as possible.

Also, another thing that has been brought up, that is definitely a gray area, is how the car performs. >0F the Civic seems to shift and do everything normally or maybe only a little sluggishly at firsts; however, unusual noises and shifting behavior at well below zero occasionally convince me that waiting 1-2 minutes idling before heading out might be in order.

I also idle the engine to warm up a little if there it's freezing-raining, the air is very moist, or any other condition that might require dry, warm air to maintain visibility.
How is "not using the heat" putting less load on the vehicle?


1. "not using the heat" cannot be found in my post. Who are you quoting?

2. Please re-read my post and see if it makes sense. Nothing I typed was cryptic or hard to understand, to be honest.

 

[gathermewool]

Originally Posted By: turtlevette
Yesterday I got out and tinkered with my cars. I started the vette and old burban and let them idle for 10 min. I let the mustang idle for over an hour while I took apart the quadrajet on the ta and cleaned it.

I think it helps to run things and get everything up to temp. Keeps the mice out too.

I feel like I have the right to use my fuel as I wish. Joyriding wastes gas too.

Commuting to a job wastes gas. Get a job working at home.

Times when I put the car in gear right away, a few times it refused to go into reverse. I don't think it's good for an old auto trans to try and shift into gear too quickly.




I think some of you are missing the point that those of us who are proponents of driving off immediately are making.

Unless the engine needs to be warmed-up to provide heat to clear the windshields or prevent poor operation (of the engine or transmission,) there is no requirement to warm up your car by idling.

If, however, you like to have a toasty warm car before getting in, then that's your decision and your prerogative. It is most likely not required for the benefit of the vehicle itself, but if it makes you happy, then that's all the justification any of us needs. It's fine, because your car is a machine is designed to serve our needs.

I take long joy rides on occasion, because I enjoy it. I don't warm my car before driving off, because I dress warmly and wasting gas to warm up my car is not worth the extra gas burned, to me.

IMO, there are limits, so even though I'm a to-each-his-own kind of guy, it does bother me when my neighbor warms his car up for 20-30 minutes.

 

[BrocLuno]

You'all don't have carburetors I guess, but I do. You'all also don't have turbos on your EFI motors, but I do. And, many of you'all don't have mixed metal castings (Iron blocks/Aluminum Heads), but I do. Can't just put thermal loads on these combinations.

And how much gas do you think you are "wasting" while you get the FM dongle to the part of your music library you want to listen to this morning...

 

[kschachn]

Originally Posted By: BrocLuno
You'all don't have carburetors I guess, but I do. You'all also don't have turbos on your EFI motors, but I do. And, many of you'all don't have mixed metal castings (Iron blocks/Aluminum Heads), but I do. Can't just put thermal loads on these combinations


You were just born special I guess....

 

[Pontual]

After doing a Runup, if in the green arc, youre good to go! The temperature on the instrument, mostly is by the aircraft manufacturer call, under engine manufacturer specs. If inside the green arc you can takeoff. Now if you are cautious, you wont slam the throttle at minimum temperature, to avoid unecessary wear.

 

[Pontual]

Originally Posted By: Garak
Originally Posted By: Pontual
Pilots do give very little warmup....

In my limited flight training experience years back, that was my experience, too. The instructor would sometimes have you warm things up a little in the cold, but no "attempts" to get to operating temperature. You'd freeze to death in a Cessna waiting for that in -30 C.

In Regina, it would be a short warmup. Checklists, taxi clearance, and not much more than that, since there isn't usually a significant amount of traffic to wait for. The lift you experience at -30 and colder is pretty darned impressive, too.


Impressive! The minimum temperature I find in here is about 30F or minus 1C, and I can tell how much more responsive the flight controls and powerplant efficiency becomes as compared to 35-40C, when it gets all muchy and slugsh, from less air density and pressure.