Engine warm-up in the morning. Is it necessary?

^^^This

My wife's Subaru has a blue "Coolant Temperature Low Indicator" light that comes on after start up. This light usually goes off after about 2 minutes once the engine has warmed up enough. You can drive while it's lit, it's not recommended that you put your foot in it until the light goes off.

 

You would feel like everyone in the Military.

 

LMFO ................How true..........

 

I live in wisconsin. Cold as fuck here all the time. i always start mine and let it idle for 15 to 20 minutes. I like it that it is warmed up in the cab for me and i drive with a very heavy foot. so i want to make sure my truck is ready to go. Before anyone posts, I know this is crazy but i like warm air. hate the winter.

 

Start it. Hail Mary it. Go.

 

For me it depends on the temp. outside. The colder it is out, the longer I let it idle. Most of the year it's only 30-60 seconds I prefer for it to warm up as I'm driving down the road.


I think it's not a good idea to start it up and park it before reaching operating temperature. You want to make sure that the engine oil is hot enough to burn off any moisture.


RJM

 

Awesome the responses this thread is getting! Thanks again for all your replies.

 

The O2 sensor is usually warmed up within 30 seconds. Closed loop at that point. Until that it runs in open loop, where it uses ECT, IAT, TPS, MAF and MAP sensors for fuel management. Of course 30 seconds is no time at all. Engines these days go into closed look operation pretty fast. Still I don't recommend a "start and go" policy when it is below freezing.

Neither is perfect, but the first option has the highest risk of long term damage if done regularly.

 

Engine warms up faster being driven than sitting idling.
Chris4x4 did a comparison, so did I. Don't recall the numbers but it was a HUGE difference... on the order of like 5 minutes vs 20 minutes before I was able to feel heat out the vents (and 10 minutes of normal driving to get the temp gauge into the normal range).

+1 to Bama. Give it 30 seconds and drive casually until it's up to temp.
Excessive cold idling is not good for the cats and can cause oil contamination from the rich mixture.

 

I warm up for about 3 minutes, then drive slowly out of the neighborhood. By that time warm air is starting to blow and the manual shifting starts to smooth out. I never jump in and take off.

 

I just drive easy on it, minimal accessories, until the engine warms up when its really cold (40s and under for us fl folks).

 

I start it up and then wait for the rpm's to drop below the 1250 mark then drive her easy and try to keep the rpm's low until the temp gauge shows the truck's up to operating temp.

Depending on how cold it is, this might be 30 seconds or 2-3 minutes. I usually plug the truck in when it gets below 10 or 15 degrees, and that sure helps a lot!

 

both of these ^^

i'm not contesting the people who say 30 seconds and go is fine; but, i wonder if they have a manual or automatic and what type of temperatures we're talking about here
the OP didn't specify "cold mornings"... he just said "morning"; I just kind of ran with the assumption we're talking about bitter cold
and in that case: my manual will not let me smoothly shift and the clutch won't smoothly disengage, short of me letting it out WAY slower than usual, until my temp gauge is between 1/4 and 1/2; and that takes quite a bit longer than 30 seconds (i'm aware the temp gauge isn't affliated with trans and clutch temps)
while i'm not prepared to say that means damage is happening, it's certainly not operating anywhere near normal 30 seconds after i start it on a -7 degree morning... and besides, it's still freaking -4 degrees, at most, in the cab 30 seconds after i start it... who wants to sit in that. haha
if it's cold out, i try to wait until the temp gauge at least budges from it's buried state

 

Ever heard a strange groan? That's your engine getting fluids in sub-zero and it takes seconds before it goes away. Ever had coolant freeze? How do you get your engine up to temp and get fluids up to temp in sub-zero? Drive your truck! If its idle is at 1500 or whatever why not just drive it and it will be around there most of the time. I've always waited seconds (or until I scrape the snow off) and then driven gently (its probably snowy anyway, or icy), and never had any related issues on any of my trucks.

 

It's been a long time since I sold a vehicle that had less that 200K on it in Maine it is not unusual for the temps to drop into the -20's. I drove a VW diesel 230K before I sold it with 327K. It would not warm up unless it was driven and if it was warm it would cool off if it sat idling. Granted a diesel is far more efficient that a gas engine but the facts still remains it takes far longer for an idling engine to warm up than it does driving. This means better mileage less oil dilution etc. By the time you have a seat belt on adjusted everything you’re good to go on matter how cold it is. An engine feels no pain not like a runner drug out of bed. So if you let it idle will the engine last 10K longer? Or maybe it makes no difference or maybe it will last 10K less will you ever find out?

 

WOW. I'm REALLY surprised nobody has brought up the point that a cold engine is out of spec.

You guys are all aware that metal expands with heat...right? You're all aware that, when cold, you cylinders and pistons have crazy amounts of gap...right? If you run an engine cold, it will cause piston slap. Maybe you don't notice it because you're busy driving at 2.5k RPM (too fast to hear it), but you ARE causing damage.

When cold, your cylinder gets bigger while your piston gets smaller. That's not even the half of it with piston rings. Piston rings barely work worth a damn when cold. Ever heard of ring gap???? The gap you leave between the two ends of the ring to allow expansion when heated up?


Anyway...your truck, not mine. Your engine, not mine. Your $3000 rebuild, not mine.

 

^ A good point, but how long do you suggest warming up your truck to minimize that damage?

 

i warm up until the temp gauge hits the first tick mark

 

In the old days, warming up the engine was the norm. Due to improvements in engine technology long warmups are no longer necessary.

In the summer 20-30 seconds just to get the oil circulating and oil pressure up.

In the winter, maybe a minute or so.... and then run it normally with no hard acceleration for the first few miles.

 

I'm not sure. I'm not an expert in metallic properties or clearances. But I do know basic chemistry attributes. Metal expands when warm and contracts when cold. I also know that a thinner oil will act like a much thicker oil when cold.
Some motors will warm up faster than others. My little 1.5l Honda motor only takes a couple minutes. With a diesel (even modern ones) it's a very unpleasant warming up process. My friend's father grew up in northern Michigan. He told me that in the 70s and 80s, people never turned their diesels off. Just let them idle all night long. Because those fuckers wouldn't start up again in the morning. Or you would kill you battery trying.

Pretty common mis-conception. Yes, modern technology is lightyears better at managing how to operate the motor, but metallic properties of expansion and contraction haven't really changed.


here's a story you guys might enjoy. I used to be a Nissan guy. I was a member of a Nissan truck forum, much like this one. I guess the Japanese like to sell lots of their trucks in Canada? So there were a lot of Canadian members on the forum. Some of them from so far north, that the high temp of the day would often be -~50F or colder in the winters.

So you all know you're supposed to regularly change the fluid in your diffs. One guy was experiencing issues with his rear diff when it was cold (lol understatement). He went to drain the old diff fluid. Nothing came out. He was worried about possible damage to the diff, so he took the housing cover off. It was so cold, that his differential fluid was one solid block.
Some other Canadian members in much "warmer" climates would report it taking hours upon hours for their diff fluid to drain.

Has it ever been so cold that your blinkers don't work for a couple minutes? Ever been so cold that your clutch just slips like ice?

Just a little food for thought when you start a cold motor in the morning. My cars take enough abuse while warm, I don't consider it fair to beat them while cold.