"Warming up" your car.

[Looneybomber]

Seemed kind of slow around here and it's fairly cold outside, so what are your thoughts?

Me? I don't warm up my car, but I drive easy till the temp gauge moves up a little bit. By "drive easy", I mean I don't go above 2k rpms. That said, it's uncommon for me to get my explorer over 2.5k rpms. My S2000 would not let VTEC kick in (which happens at 6k) and had a rev limiter that would engage at 6k if the engine was not over a certain temp.

My roommate warms up his car everyday. We're 1.5mi from school (4min drive) and today he let his car warm up for 12mins. While there's nothing wrong with this and taking getting an engine up to temp for 15-20min every once in a while is required if you primarily make short trips, but I find it wasteful and not needed on a daily basis.

If this has been discussed ad nauseam, then ignore this thread. Just seemed like we could use a little more activity around here.

[ddgsxr504]

Its not a bad idea to let your car "warm" up a little before driving. My 95 240sx has 251,000 miles on it and I let it warm for about 5 min or so just to get the oil heated up. Cold oil does d!ck for your engine. If you live in a cold climate it is def beneficial. I think 12 min is a little excessive but then again he may want the heater to work properly for his short trip to school. Its been proven that short trips are bad for the engine as the oil never fully heats up thus it doesn't properly lubricate the engine. Just my two cents anyway.

[MinisterofDOOM]

Unless temps are incredibly cold (below freezing) there's not much point.

I never bothered to "warm up" my Maxima and at 280k it didn't use any oil or leak a single drop, and oil analyses came back clean.

However, in ~-15 degree Idaho winter temps, my LS8 sounds like a Powerstroke after startup. I'll let it idle for a couple minutes before heading off. Waiting for things to get up to "normal operating temps" would take a long time, and simply isn't practical (or necessary). But getting the oil flowing and heating things up is worth a couple of minutes.

My current commute is .5 miles. I'd walk but for most of the winter it is far too cold to be tolerable (again...-15). So I start the car, wait a couple minutes, and head out. The trans usually sounds a little whinier than normal in 1st (straight-cut) but shifts fine and behaves normally. ATF is very low-viscosity stuff anyway so it doesn't thicken up much in the cold.

[Dattebayo]

Block/engine heater.

My old company had them on all the fleet vehicles so we didn't waste time warming up and "getting coffee" at the start of the day.

[skydragoness]

The RS has highish miles (186k); I let it warm up if it's below freezing out--but i do it more for the transmission than the engine. The transmissions on these cars are delicate and I noticed if I don't let it warm up enough the shifts aren't smooth and there's some resistance. I suppose since it takes a lot longer for the transmission fluid to get warm (it's a Redline mix). I usually take the long way around to the on ramp to the highway (that's right by my house ) to give it a chance to do it's thing.

[Bubba1]

This myth has been around as long as people who put "premium" gas in their cars that are designed to run on regular "because their baby is worth it". Yes, it was recommended long ago let a gas engine to warm up back when most cars had carburetors and manual chokes. But that's no longer the case. In modern fuel injected cars, especially those equipped with synthetic oil, you only need to let it warm up enough to get the fluids circulating. We're talking seconds here, not minutes. Letting a modern car "warm up" beyond, say 30 seconds is a waste of gas. The most important difference between driving a cold car and a warmed up one, is you should avoid driving a cold car HARD until the fluids get closer to operating temperature. Your gas mileage might briefly be lower driving a cold car, but it's a whole lot better gas mileage than letting the dang thing sit and idle. And you won't be damaging your engine by driving it cold.

[krash]

When my car was stock, I never really worried about letting it warm up. But like bubba said, I never drove it hard unless it was warmed up.

With forged internals, I have to let it warm up or the pistons start slapping. I can usually get away with short drives (under 2k) if I absolutely have to. But I usually let the oil temp get to 140ish before I drive somewhere "normally"

[Looneybomber]

That's interesting. Why would forged internals make a difference?

[krash]

They expand with heat, so they're made a bit smaller than the cylinders. When your engine is at operating temp, the cylinders are expanded to the size that they need to be and no more slap slap.

[Dattebayo]

Ah, now I understand why a catch-can is needed when you upgrade to forged. I always wondered about that!

[asoomal]

The RS has highish miles (186k); I let it warm up if it's below freezing out--but i do it more for the transmission than the engine. The transmissions on these cars are delicate and I noticed if I don't let it warm up enough the shifts aren't smooth and there's some resistance. I suppose since it takes a lot longer for the transmission fluid to get warm (it's a Redline mix). I usually take the long way around to the on ramp to the highway (that's right by my house ) to give it a chance to do it's thing.

I just bought a GC4 and what you said couldn't be any more true.

In the mornings, you can barely move the gear shift lever, and there's a huge drop in RPM when I release the clutch when in neutral while it's warming up....shows how much resistance there really is.

[Ajax]

In the mornings, you can barely move the gear shift lever, and there's a huge drop in RPM when I release the clutch when in neutral while it's warming up....shows how much resistance there really is.

Mine has done the same thing. There are even mornings when the car will lurch forward just a bit when I let out the clutch from startup.
Only on days when its been below -10 overnight do I bother with letting it idle for more than a few seconds. Otherwise its just low rpms and very slow shifting. Occasionally, I'll shift from 1st to neutral and let the rpms drop before shifting into 2nd- otherwise I hear a horrible grinding.
I remember when I first brought my 240 to MN (I now drive a Protege as my daily), I had Redline's heavy Shockproof gear oil. That first subfreezing day with a transmission popsicle led me to the shop to change it out as soon as I could.

[Loki]

In modern cars letting it idle for more than a minute or two is just gonna kill your fuel economy more than anything.

The RS has highish miles (186k); I let it warm up if it's below freezing out--but i do it more for the transmission than the engine. The transmissions on these cars are delicate and I noticed if I don't let it warm up enough the shifts aren't smooth and there's some resistance. I suppose since it takes a lot longer for the transmission fluid to get warm (it's a Redline mix). I usually take the long way around to the on ramp to the highway (that's right by my house ) to give it a chance to do it's thing.

Does that RS have some sort of ATWU system? I don't see how letting the engine sit idling would warm up the trans fluid.

[asoomal]

Some parts of the transmission are in motion when in neutral with the clutch disk engaged.

It somewhat helps warm up the oil.

[Bubba1]

FWIW, your engine warms up more quickly by driving it rather than idling.

[Loki]

Some parts of the transmission are in motion when in neutral with the clutch disk engaged.

It somewhat helps warm up the oil.

Ah I can see it now. Transmissions are still mostly metal boxes full of witchcraft to me.

[Kompresshun]

Personally i've never really let an engine warm up much, unless it's really cold outside and I want the car to be warm inside before I take off.

Typically I just hop in the Sorento or the Five Hundred and let them run for 30sec-1min max before taking off. With the Miata, I will let it warm up for a few minutes on really cold mornings, if I have time. Since it's older and has more mileage on it, I try to not beat on it too hard when it's cold. Even with it, I only let it run for 5min or so max and i'm not too worried about it if I don't have time to warm it up. I just don't take it past 3k rpms until it gets warm.

[WDRacing]

I warm up my car for a few minutes when it's cold out. It takes about 3 minutes before the seat heaters kick in!

Seriously though. The oil itself doesn't lubricate, nor flow as well until it's up at operating temp. That pretty much applies to the entire motor. It's designed to run at operating temps, not cold. From metal expansion to lubrication and all things in between.

You can disagree all you want, but the only negative thing about warming up the vehicle is a slight...very slight, usage of fuel.

However, allowing your engine and all it's systems a little time to work there way up from very cold before you apply any load to the engine is beneficial in every aspect. I'm not suggesting everyone go have a cup of coffee, 3 minutes is fine.

[Bubba1]

I warm up my car for a few minutes when it's cold out. It takes about 3 minutes before the seat heaters kick in!

.

Yep, heated seats is a requirement for any vehicle I buy for my wife, and 3 minutes can seem like an eternity given the cold winter we're having. Though she does not appreciate my alternative heating method of my consuming Mexican food and beer the night before...

[flohtingPoint]

Competition driving: I wont leave grid until my oil temp reaches a certain level (different for each car, but it's certainly not, turn on and go).

Regular driving: Get in, start truck, buckle seatbelt, get going.

[skydragoness]

I warm up my car for a few minutes when it's cold out. It takes about 3 minutes before the seat heaters kick in!

Seriously though. The oil itself doesn't lubricate, nor flow as well until it's up at operating temp. That pretty much applies to the entire motor. It's designed to run at operating temps, not cold. From metal expansion to lubrication and all things in between.

You can disagree all you want, but the only negative thing about warming up the vehicle is a slight...very slight, usage of fuel.

However, allowing your engine and all it's systems a little time to work there way up from very cold before you apply any load to the engine is beneficial in every aspect. I'm not suggesting everyone go have a cup of coffee, 3 minutes is fine.

Agreed!
Every car/engine is different too, it takes oil longer to circulate around a v6 or v8 vs a 4 cylinder. Generally when it's cold out I let my Subie get up to the 'C' mark before I start driving (gently) which seems to take about 5min. I'm so done with winter at this point...I feel like I'm living in NY again.

[WDRacing]

Crazy weather this year! I'm quite ready for winter to be over.

[Looneybomber]

Ah, now I understand why a catch-can is needed when you upgrade to forged. I always wondered about that!

What about engines with forged internals from the factory. I don't think they have catch cans, or do they?

[float_6969]

Not all forged pistons have that characteristic, but the major ones do. It's only the pistons that have this effect. The rings still seal properly when cold, it's just that the piston-to-wall clearance is too great when they're cold, causing the piston to "slap" in the bore. This can cause scuffing on the piston skirts and wear on the cylinder walls. THAT can cause blow by issues. The forged piston in-an-of itself doesn't require catch cans. The reason most forged engines run catch cans are because they usually run more end-gap on the piston rings. This causes more blow-by, and so a catch can is needed.

As for OEM forged pistons, there is another type of forged aluminum alloy that is a low thermal expansion type that doesn't suffer this side effect. On paper, it's not as strong as the other type, but I don't know that it's ever been proven to be weaker either.

[Looneybomber]

Ok now that is some good info! I assumed the same alloy was used throughout, but according to Wiki, "Aftermarket performance pistons made from the most common 4032 and 2618 alloys are typically forged." SCIENCE!

[float_6969]

Yea, the common alloy is the 2618. That is the high thermal expansion type, but is more malleable, so it's less prone to cracking under detonation. The 4032 is the low thermal expansion type, and is harder, but more prone to cracking COMPARED TO the 2618. That being said, compared to a normal cast piston, it's still WAY stronger and WAY less prone to failure due to detonation.

I actually purposefully switched away from the 2618 for the reason of dealing with the piston slap when cold, and the scuffing that it caused on the skirt and cylinder walls on my motor. Don't get me wrong, it's not like the motor was ruined, but for a street/strip motor that would be exposed to low Kansas winters, I couldn't stand to build another motor that I had to listen to beating itself up every time I started it in 20° weather.

[WDRacing]

Also, engines with forged pistons usually have them for a reason. That reason is usually very high cylinder pressures associated with very high compression and or boost of some sort. High cylinder pressure leads to more blow-bye regardless of piston type. Forged pistons absorb the load without breaking far better than standard cast pistons. The downside to forged pistons is they require room for thermal expansion, like Float mentioned. Hence the slight piston slap.

[krash]

Not all forged pistons have that characteristic, but the major ones do. It's only the pistons that have this effect. The rings still seal properly when cold, it's just that the piston-to-wall clearance is too great when they're cold, causing the piston to "slap" in the bore. This can cause scuffing on the piston skirts and wear on the cylinder walls. THAT can cause blow by issues. The forged piston in-an-of itself doesn't require catch cans. The reason most forged engines run catch cans are because they usually run more end-gap on the piston rings. This causes more blow-by, and so a catch can is needed.

As for OEM forged pistons, there is another type of forged aluminum alloy that is a low thermal expansion type that doesn't suffer this side effect. On paper, it's not as strong as the other type, but I don't know that it's ever been proven to be weaker either.

Most aftermarket forged stuff will be the 2618. Wiseco does offer 4032 as well, but the 2618 is more popular.