Warm up car???

[ajaxlupis]

Should you warm up a car before you go?  I live in Southern California so the cold temperatures aren't an issue for us.  That said, is it beneficial to let a car (we have a 2013 Honda Fit and a 1998 Toyota 4-runner) warm up, or should we just start it and go?

I could imagine that letting the car warm up reduces wear and tear.  Also maybe warming up allows for better gas mileage.  But I don't really know those things all that well.

Any help would really be appreciated.

Thanks

[hunniebun]

I am not an expert, but I would say that if you live in a mild climate there is no reason to let your car warm up. I live in the north where temps are routinely -30C in the winter and it is recommended that a car warm-up for a minute or two before shifting it into gear to avoid stalling, but otherwise I just start and go...even when it is -10ish. I'd be interested to hear from someone who actually knew something about cars!

[dycker1978]

It does not benefit my bike ride to warm the car first :P

But seriously I have read that at any thing colder than -10 Celsius you should let it warm, but any more than 5 minutes is a waste.  Any warmer than that and you don't need to warm it.  It had little to no effect of the mileage and wear and tare.  I have lived by this in Saskatchewan where the temp routinely goes to minus 40 or 50 Celsius in winter and as high as plus 40 in summer with not issues to my vehicle.

[YK-Phil]

I live in Yellowknife, where we possibly have the steadiest low temperatures in North America. I no longer own a car here but when I did, I would only let it warm up in winter for a maximum of 3 minutes before driving, at very low speed for a couple of minutes. At -30, it's actually more a problem for the tires that are frozen square and will take a good five minutes to regain their shape.

[JLee]

You should let it run for a few seconds to build oil pressure (i.e. don't start it with your foot to the floor).  From what I have read, the general consensus on this topic is that you will have less engine wear if you don't let the car idle to warm up, as that's a longer period of time the engine is running while cold. It heats up faster when driving.

I don't have studies behind that, though - and you do want to make sure you're at operating temp before you push the engine hard (i.e. don't take a car, especially turbocharged/supercharged, and run it to redline with cold oil - and keep in mind your temperature gauge is for coolant, not oil. Oil takes longer to warm up).

[HipGnosis]

I am the son and grandson of professional mechanics.
I have rebuilt multiple engines and built some custom ones from scratch.

Even knowing the advances in materials, assembly processes and tolerances and oil technology, I physically cringe every time I see someone start their car and immediately put it in gear and slam on the gas.
It takes a few seconds for oil to get everywhere it needs to be and for coolant to circulate.  And engines are more efficient when at operating temperature.
I always start the car, put on seat belt and check mirrors etc. before putting it in gear.
And in winter (I'm in Wisc.) I give it about a minute of idling before giving it any gas.

[Syonyk]

Should you warm up a car before you go?  I live in Southern California so the cold temperatures aren't an issue for us.  That said, is it beneficial to let a car (we have a 2013 Honda Fit and a 1998 Toyota 4-runner) warm up, or should we just start it and go?

Southern California does so get cold!  68F is frigid and is parka weather, 70F is perfect, and 72F is hot and swimsuit weather. 69F and 71F are grounds for complaining on Twitter. :p

Modern gas cars don't need much warming up.  Unless it's really cold (and for you, this situation will never exist), start it, let it idle for 15-30 seconds to get the oil all the places it should be, then drive gently for the first few miles until the temperature comes up.  Emissions laws require very aggressive control of startup emissions, so the "go stupid rich for a long while" startup methods of older cars are no longer a thing.  You don't have a choke to worry about anymore. :)

A long warmup is just burning gas and not accomplishing much of anything useful with a modern fuel injected vehicle.

Old cars are a different story, but you don't own anything old enough to worry about it.  Diesels can also be pretty picky, but if they're cold blooded, they at least come with block heaters. :)

I physically cringe every time I see someone start their car and immediately put it in gear and slam on the gas.

It's worse when you see someone do this to a cold airplane engine. :(  They're *expensive* to rebuild!

[GuitarStv]

In the winter when it's -20 out, 30 seconds is all the warm up your car needs. More than that and you're wasting gas.

I wouldn't recommend slamming on the gas immediately after starting a car . . . but I wouldn't recommend slamming on the gas pretty much ever in a car.

[nereo]

It's worse when you see someone do this to a cold airplane engine. :(  They're *expensive* to rebuild!

OT, but do pilots ever actually do this? I mean, start their engine and then go full throttle and take off?  Seems like something you'd only see in a Bond movie...

[BlueMR2]

OT, but do pilots ever actually do this? I mean, start their engine and then go full throttle and take off?  Seems like something you'd only see in a Bond movie...

If they are, they haven't read the operating handbook.  All the ones I have specify a minimum oil temperature for takeoff power.  However, it is very common to pre-heat the engine when it's cold, so even if you see someone jump in, do a quick runup, then takeoff, it may not actually be a cold engine.

For the car...  Generally speaking, the best way to warm up a car is to drive it gently.  As mentioned above, that doesn't mean jump in and go.  Start it up, let it get oil pressure, THEN start going.  Slow steady acceleration, don't rev too high, but don't lug it either.  Some exceptions are when it's really cold, some cars may not be happy about going into gear until they've warmed up some (my Mitsubishi won't go into gear until the RPMs come down to 1700).

[Posthumane]

It's worse when you see someone do this to a cold airplane engine. :(  They're *expensive* to rebuild!

OT, but do pilots ever actually do this? I mean, start their engine and then go full throttle and take off?  Seems like something you'd only see in a Bond movie...

While I haven't seen anyone take off without a few minutes of warm up time first, what I have seen a fair amount of is using way too much primer and too large a throttle opening on startup. It's painful to watch someone cranking the engine on a cold day and having the RPMs shoot up to 1500+ rpm when it first catches.

With regards to the car, there is no need for a prolonged warm up period in California. As BlueMR2 states, drive it gently for the first minute or two (by avoiding high RPMs and high cylinder pressures). My car warms up at about 15 C per minute initially, and anything above 40 C coolant temp is good to go for moderate power levels. This means that even in the winter time with temps around -20 C, a couple of minutes of idling in the driveway while scraping off the ice followed by a couple minutes of gentle driving through a residential area before getting to the highway is adequate.

[Syonyk]

^ Yeah, I was referring to 1500 RPM starts.

[RWD]

You should let it run for a few seconds to build oil pressure (i.e. don't start it with your foot to the floor).  From what I have read, the general consensus on this topic is that you will have less engine wear if you don't let the car idle to warm up, as that's a longer period of time the engine is running while cold. It heats up faster when driving.

I don't have studies behind that, though - and you do want to make sure you're at operating temp before you push the engine hard (i.e. don't take a car, especially turbocharged/supercharged, and run it to redline with cold oil - and keep in mind your temperature gauge is for coolant, not oil. Oil takes longer to warm up).

This is what I've heard as well.

[Sibley]

I'm in Chicago, and saw an article this winter saying it needs 30 seconds, unless you have a really old car. I just wish I were warmer!

[Pooja Sharma]

If you're not in hurry then you should always warm up your car first and then go
It actually reduces wear & tear

[Syonyk]

If you're not in hurry then you should always warm up your car first and then go
It actually reduces wear & tear

That's less true on modern vehicles, and many of them will run the engine at a high RPM anyway on startup for cold start emissions (which isn't actually great on the wear side of things).

Gentle driving warms things up smoothly as well, and also has the nice benefit of warming up the transmission fluid, which idling in the driveway won't.

[guitar_stitch]

Warm ups applied mostly to carburetor vehicles where the cold temperatures were difficult to account for on a physically regulated metering system.

Fuel injected vehicles handle the cold based on feedback from various sensors and adjust the fuel ratio and timing accordingly.

That said, there are still some laws of physics that cannot be overcome in most cars (at a price acceptable to the manufacturer)...

A routine that has worked well for me in the moderate temperatures of Jacksonville (even when we get to sub-freezing):

1) Start car, check mirrors and gauges while fastening seat belts.
2) Disengage parking brake.
3) Drive.

During the first 5 minutes or so, I try to be gentle on the engine.  There is still some thermal expansion to be accounted for in a cold motor.  My Honda Element is very chatty in the valve train if I get too spirited.

The 30 second estimate is a good number.  Beyond that, you're just wasting fuel and increasing the wear on components (cold temps, viscous oil, low oil pressure due to idle speeds)

[Greg]

An idling engine takes longer to warm up than one being driven, and a cold engine uses almost 2x the fuel of a warm engine.  A lot of that excess fuel doesn't actually burn in the cylinder, and causes excess wear and dilutes the oil.  Not to mention increased emissions.  The best practice is to star the car, and after maybe 30 seconds to let everything get circulating, drive gently.  If your route puts you immediately onto a freeway, warming it up until the temp gauge starts to rise is a good idea.  In any case you should at least make sure you can see out (defrost/scrape) before getting underway.

[daverobev]

Get in car
Put seatbelt on
Put key in ignition; turn to 'run'; hear fuel pump finish priming
Start car
Hear higher than normal idling revs
Wait for idle revs to die down to normal
Drive