Should You Warm Up Your Car Before Driving?

[69GTX]

Originally Posted By: Shannow
Originally Posted By: 69GTX
Oil is the thickest before you cold start the car. The colder it is outside, and the longer the car has sat, the lower the viscosity...regardless if it's a multi-grade or straight weight oil.

From that point on, the oil only gets thinner as oil temp rises. It would be ideal if the oil at startup were around 8-14 cSt (operating viscosity ranges). It's actually up to 1,000X to 3,000X that during an extreme cold start in say -35/-40 deg C temps. Time to read the new Motor Oil University...or even the old one.


I disagree...if the oil was at operational viscosity at startup, it would need all the AW additives to be fully functional from dead cold...which they don't.

The thicker, cold oil does a fair bit of hydrodynamic lubrication in the period between first start, and thin/additive controlled wear.


Logically, if the oil is at operational viscosity at startup, your car was already hot and just turned off. But I would agree that you'd want the oil preheated at S/U if possible so that the AW additives are functioning. And that's achievable with today's technology. Can there be such a thing as an oil that starts off at 10 cSt at -20 deg C and can function in a car's engine at 100 deg C?

 

[SwampSurvivor]

Originally Posted By: supton
Originally Posted By: Miller88
Originally Posted By: Kamele0N
Originally Posted By: Miller88


If it's the Focus or the F350, I will usually wait for it to idle below 1500 before taking off. Both will idle at 2500 when first cold started.


Are focus and F350 ancient carbureted versions with manual choke? Pretty insane rpms for cold idle for car with ECU and injection...


The F350 is a 2001, focus is a 2011. My old 2001 Taurus would do the same thing.

It's ridiculous, but they MUST rev to crazy high RPM when cold for some reason. My taurus, if cold started and put right into drive, would accelerate up to 25 or 30 on its own. The truck and Focus are manual transmission and it's a pain to shift them when cold - as soon as you push the clutch in, they rev right to 2500 again.

All three have been to the dealer for it and it's "normal" apparently. Lights the cat(s) off.


Higher rpm, heats up faster. More importantly, it probably heats up the catalyst faster. There are cold start limits to be obeyed. Also, I wonder if the higher rpm helps with transmissions: a manual trans will heat up a bit, even in neutral. I could tell in my TDI what a few minutes of idling would for shifting. An automatic is no different, although the pump likely makes far more heat (then again, thin ATF shouldn't need much heating I'd think).


What I used to do when I commuted with the F350 was put the transmission in gear and transfer case in neutral. That did a good job of circulating the fluid and warming it up. Shifted like it was summer!



Originally Posted By: Branson304
Originally Posted By: blupupher
I just love all these "keep it under 3000 rpm" lines.
Not everyone drives a small engine vehicle. 3000 rpms in my 5.4 is pretty excessive.

I don't understand the problem. Isn't the whole reason to get 0w and 5w oils to have good cold weather oil flow? Why would you need to wait for the oil to warm up (which will make it thicker) before driving?


Good God... please do some more research on what oil viscosities mean in the real world.

And 3K RPM while cold isn't excessive for your 5.4L. I've put hundreds of thousands of miles on big V8s with my "under 3K cold start" rule with absolutely no engine issues.


Towing with a 5.4 pretty much mandates 3000RPM. If there is a hill within 3 miles, you're going to be slowing down unless the engine is between 3000 and 4000!



Originally Posted By: Wolf359


Yeah, that was normal for the Taurus that I had before. Other thing would be that the transmission needed to heat up too before the lock up torque converter would kick in. It just wouldn't engage til the fluid was warmer, seemed to take about 5 miles or so in the cold, only a mile or two in regular weather. It was easy to tell as the rps would be about 200 higher if the lockup didn't kick in.


I had a pretty large transmission cooler on mine. If the temperature was really cold out - 0F or so, I could drive to work and it wouldn't lock at all because it never warmed up enough.

 

[zeng]

Originally Posted By: Shannow
Originally Posted By: 69GTX
Oil is the thickest before you cold start the car. The colder it is outside, and the longer the car has sat, the lower the viscosity...regardless if it's a multi-grade or straight weight oil.

From that point on, the oil only gets thinner as oil temp rises. It would be ideal if the oil at startup were around 8-14 cSt (operating viscosity ranges). It's actually up to 1,000X to 3,000X that during an extreme cold start in say -35/-40 deg C temps. Time to read the new Motor Oil University...or even the old one.


I disagree...if the oil was at operational viscosity at startup, it would need all the AW additives to be fully functional from dead cold...which they don't.

The thicker, cold oil does a fair bit of hydrodynamic lubrication in the period between first start, and thin/additive controlled wear.

At 8-14 cSt, engine plain bearings at idling speed of 650 rpm or so would be in hydrodynamic lubrication regimes though ring/cylinder and valve train would encounter boundary lubrication regimes that calls for AW additives activation.
I suppose modern engine oils would contain sliding-activated AW additives that works at low temperatures, besides temperature-activated AW additives .

 

[edyvw]

Originally Posted By: KrisZ
Originally Posted By: edyvw
Really, so your answer is being slave to another. Do enlighten me!
I can actually follow temperature on phone and when you turn heat there is sudden drop of temperature as water from heater core is released.
I posted very detail explanation, so go ahead...


I read you post carefully. You claim that one practice is a myth, i.e idling the car to prolong its life, while you developed your own ritual because it shaves off few minutes in reaching operating temp. Why do you think you should do it?
If the answer is to prolong engine life, then you substituted one myth for another.

Prolonged engine life?
1. Heat comes faster. Putting HVAC on heat immediately delays any heat longer. Putting HVAC on cold and in 2-3 minutes I have pretty decent air to easily warm up pretty big interior.
2. I can warm up oil faster and drive it the way I want, that is it.
But bottom line is, this way I actually have in 2-3 minutes more heat coming thru vents then if I was going other route.

 

[Tomioka]

I take off when the seatbelt light stops flashing (then I put on my seatbelt before backing out). By then the valvetrain clatter disappears.

 

[Wolf359]

Originally Posted By: edyvw
Prolonged engine life?
1. Heat comes faster. Putting HVAC on heat immediately delays any heat longer. Putting HVAC on cold and in 2-3 minutes I have pretty decent air to easily warm up pretty big interior.
2. I can warm up oil faster and drive it the way I want, that is it.
But bottom line is, this way I actually have in 2-3 minutes more heat coming thru vents then if I was going other route.


I think you're missing the whole point of climate control. I don't play with the buttons, it's already set the way I like it. As others said, the vent starts off slow then picks up speed as it starts to heat up. This way I don't have to remember to turn it on in 3-4 minutes. The only annoying thing about duel climate control is adjusting the passenger temperature back.

 

[SevenBizzos]

LOL. This comes up a few times every winter and it seems you're on one side of the line or the other. Some of these articles near fear mongering about engine damage by warming, but there's no statistical evidence (that I've read) proving warming directly shortens the life of your engine.
It was just -14F a few mornings ago and there's no way I'm starting and going - for a lot of reasons. If that's what you do, good for you.

 

[mclasser]

Originally Posted By: Wolf359
I think you're missing the whole point of climate control. I don't play with the buttons, it's already set the way I like it. As others said, the vent starts off slow then picks up speed as it starts to heat up. This way I don't have to remember to turn it on in 3-4 minutes. The only annoying thing about duel climate control is adjusting the passenger temperature back.

ACC is annoying in the winter, IMO. It blows at your feet or the windshield but doesn't switch over to the face vents. My cold hands want some warmth, too.

 

[OVERKILL]

Originally Posted By: mclasser
Originally Posted By: Wolf359
I think you're missing the whole point of climate control. I don't play with the buttons, it's already set the way I like it. As others said, the vent starts off slow then picks up speed as it starts to heat up. This way I don't have to remember to turn it on in 3-4 minutes. The only annoying thing about duel climate control is adjusting the passenger temperature back.

ACC is annoying in the winter, IMO. It blows at your feet or the windshield but doesn't switch over to the face vents. My cold hands want some warmth, too.


That's what a heated wheel is for, LOL!