Cold start

>Keep all of your engine components as cold as possible while it's running for best performance!

>OMG don't rev your car on a cold start or drive it immediately, everything is still cold!

Well Veeky Forums, explain this shit. Which one is it?

Well, the first one is definitely wrong. Engines run at hard 90C to minimize cooling losses. That's why they have thermostats. Take off your thermostat and see what kind of performance you get.

The second one is kind of wrong. It really depends on how cold we're talking about, though. Idling in a parking lot is not doing your drivetrain any favors, however.

The "cold" in the first sentence is about a 120 degrees hotter than the "cold" in the second sentence.

>Idling in a parking lot is not doing your drivetrain any favors, however.
So what SHOULD you do to properly warm up the engine?

So if theres a 120 degree difference then wouldnt you want it at the coldest point for the bigger bangs?

Basically low stress driving consisting of modest acceleration and never really pushing your enging to the limit.

You're aiming for the kinda usage that keeps your oil pump at a decent output while not demanding too much of the still (relatively) cold oil. Also metals expand as they heat and heating them too fast can cause them to deform unevenly. If this happens it can cause increased wear and severe damage.

Basically don't idle for hours at a time or start up your car and run it at red line immediately.

Neither.

Cars have an optimal operating temperature they need to run at so getting it up to that temperature as quickly as possible is most ideal to minimise wear.

However, you shouldn't thrash a cold engine to get it up to temperature quickly because the tolerances of the engine are much greater cold than hot, which will promote greater wear and risk of failure.

The correct procedure is to let the engine idle for a minute or so, then drive sedately (i.e. under 2-2.5k) until the engine is up to temperature.

>Idling in a parking lot is not doing your drivetrain any favors, however.

No, but it gets the air moving in the couple of minutes it takes me to get settled and moving, or powers the heated windscreens in winter while I scrape the ice off.

anybody that doesn't immediately rev their engine to 6k rpm upon starting their car regardless off temperature is a fucking moron.

gotta warn your engine about whats ahead

This desu, how else would you warm up the engine.

It would take like 5minutes of just idling.

The correct way is to drive slowly with verry little thottle and rpm untill you have a decent temperature.
I suggest not more than 2000 rpm and 300 mBar.

At that cold of levels, the cold parts would actually start absorbing the combustion energy instead of turning it into mechanical energy.

Like most everyone has pointed out; first one is entirely incorrect, as there is an optimal performance temperature where your engine is at its best performance, with as minimal heat loss as possible and the entire system running at full capacity and lubrication.

When the engine is cold you are nowhere near the full capacity of the engine, as the metal parts are cold and contracted, and will heating up and expanding at a rapid rate until the aforementioned optimal operating temperature has been reached, at which point the temperature will be relatively consistent due to how the cars automated cooling system works

The effects of idling your engine while its cold is often the subject of debate. I think most of the horror stories you hear stem from the time where cars did not have the fine-tuned oil pumps and filtration systems we have today, nor the superior quality oil that we also have today, with many different ratings for how well they perform in colder temperatures and whatnot.

I like to think that today, with a modern engine thats in good shape, and the right oil for your temperature it does not make much of a difference wether you drive calmy/normally until it has heated up, or let it idle for a few minutes. The oil should be sufficiently fluid from the beginning, and lubrication should be instant

I wouldn't approach the high RPM's before it had gotten the opportunity tho, as higher RPM's mean you need a higher oil pressure to keep the lubrication up aswell as cooling for the oil, and after a cold start the oil is not perfectly fluid like it will be when the engine has reached optimal temperature

I live in Canada.

We get - 40 c here regularly.

If I plug in my car the night before, or let it idle for a bit before I take off I'll save alot of fuel for my daily commute. I also blank off my radiator with cardboard. This helps a lot.

When I first take off I can feel my rear differential dragging when it's that cold.

Have I taken off immediately on such cold days? Yes. But I paid for it in fuel, and it sounded like shit until it finally warmed up.

I can also tell you it'll take some time for the jugs to seal up too, for any engine. This is why compression values are higher when the engine is hot.

>blank out the radiator with cardboard

Isn't that what the thermostat is for?

driving at -40c the air passing through would cool any heat produced for the first few minutes, prolonging the time to warm it up. this is only really practical for suvs and trucks, since the rad is huge

It sure is.

But when you introduce - 40 coolant you'll just set the engine back to rich again.

I do this on my ranger. Makes a big difference at those temperatures, when you drive 2hr on the highway every day.

we do the same on our ferd work trucks, bigass quilted leather bug screens really help

This and let the auto choke turn off before you drive when you cold start and the engine revs about 400 more rpm then drops to normal rpm.

>user you need to let your brand new shitbox warm up for at least 10 minutes or else you'll break it!

Just wait for auto choke its like 30 seconds and then you need to drive to build oil pressure.

Drive a semi,company said NEVER do that,but they were new trucks,and a semi...just saying.

>90C

Wew lad.

diesel trucks are a different beast all together. When it gets real cold though you'll need tank and line warmers to keep the fuel from jelling, and you switch your air intake to pull air from inside the engine bay so your not trying to compress -40 air and jello diesel.