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warming up the car...does it really do anything?


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I've heard conflicting opinions about warming up the car...i.e. letting it idle until the temp gauge passes the "C" mark. Some say it helps, others say that the oil circulates after 30 seconds and that letting it idle anymore is useless.

 

whats the skinny on this, specifically for our cars? (mine's a 2.5i specifically)

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1) You waste gas while idling

2) You have more emissions while idling because the cats don't warm up

3) Even if your engine has warmed up a bit, the rest of your car is still brick-ass cold, like your tranny, suspension, brakes, axles, differentials, etc. etc.

 

SO even if your gauge gets to the mid-point from idling, you should NOT be thrashing on your car until EVERYTHING has warmed up.

 

In conclusion, drive around GENTLY until your car is fully warmed up. And remember, even when the temperature gauge has reached the middle, it doesn't mean everything has warmed up yet. And that includes your engine oil.

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If it's below 20f or so, I might sit and let the car idle for 30 seconds to 1 minute. After that, I'll drive the car gently till its warmed up like invar and nouse said.

 

If its below 35f or so, I'll let the car sit for 15-30 seconds, and again just drive gently till its warmed up.

 

Also this is only if the car has been sitting outside in these temps for awhile, say more than 2-3 hours. If I'm out doin errands or something and it's cold out, I'll usually just get in and go without waiting.

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Start it and drive it easy, it's common for all new cars.

 

 

These engine tend to wear the pistons more when idleing when cold. The oil gets deluted by the extra gas when the engines cold.

 

It's -2F here now, after I load the skis in the wagon I'll start it, wipe the snow off and then drive the mile to the mountain. Tomorrow when its -16F I'll do the same thing.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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I let it idle until the SAP goes off, than I drive slowly until oil temp reaches a decent level.

 

It took almost 10 minutes of driving today before the temp guage reached its normal spot. I can only imagine how long it would take if someone let it idle.

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I let it idle until the SAP goes off, than I drive slowly until oil temp reaches a decent level.

 

It took almost 10 minutes of driving today before the temp guage reached its normal spot. I can only imagine how long it would take if someone let it idle.

 

Less time typically since there is very little airflow to cool.

 

My biggest concern with a H4/H6 design is that the weight of the pistons are placed on half the piston head. Unlike a inline or V design where most of it is on the bearings. It's a very thin coat of oil that stops you from ruining your rings.

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I let mine idle till 100 degrees on my accessport gauge. I have forged pistons and the knock sensor picks the piston slap up as knock retarding the timing so much the car is almost un drivable if I don't. I choose 100 though because it seems to be the sweet spot for piston to expand enough so knock sensor does not pick it up and car is drivable, I did not pick it because there is any scientific study behind it
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The newer engines go through temperature cycle torture tests to replicate the most extreme conditions. Cold startup, max power til oil is hot, then immediate shutdown. Pump frozen coolant thru the engine to bring it down to -22F, and repeat the process hundreds of times. There is a neat article in this month's Car and Driver about it.
LW's spec. B / YT / IG
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As soon as your oil light is out you can drive. Just use your head, go slow the first mile or so and let the gear lube "wake up" and just don't rev the piss out of it until your up to operating temp. Otherwise all your doing is wasting gas in my opinion (but it is nice to get into a warm car).
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While I know nothing about Subaru's in particular, and very little about how horizontal cylinders would affect the issue, this is something I have looked into. Modern engineering tolerances (and oil tech) have improved the functionality of engines to the point where the load of driving warms the engine up faster than idling. With oil circulating regardless, on the road the car ends up turning much fewer total rpms while cold and so causes less wear on cold components. As was stated above, a warm engine guarantees neither warm oil nor warm power train components. Many people I know warm their cars up so they can jump in and beat the shit out of their car. Bad idea. Automatic transmissions benefit more from idling, as fluid circulates through the torque converter it builds pressure in the rest of the system and warms it slightly. An older car (80's and earlier) with a less efficient oil pump does benefit from warming up.

The conclusion I've come to is this. If you want your car to last a long time and care for it obsessively, idle for 30ish seconds and drive gently until the whole car is warm. If you care more about having fun just jump in and beat it, because you don't care anyway. If you value your comfort more, let it idle for a while, it won't do that much damage. Now that my car has been relegated to beater status, I'll let it idle for 15 minutes until it is nice and toasty :-D

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  • 4 weeks later...
Hope I'm not posting in a dead topic, but how about when it is ridiculously cold outside? I live in Northern Colorado and it was -24 (yes, NEGATIVE) this morning. Should I still only let it warm up for 30 seconds for the first start-up of the day?
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30 seconds won't hurt, nor will it make a difference.

 

But 30 seconds is not what we're really talking about. it's the 5 or 10 minutes that some do.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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i let it warm up for 30 secs and then drive, keeping it below 2500 rpm until the car reaches full operating temp.

 

sometimes there is a red light right after i pull out of the garage, and the car is left warming up stopped, in Drive ( i have an automatic) . it feels very rough when it does this, like it is pulling hard to go...should i put it in neutral while it is still cold at the stoplight?

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I don't have any of the roughness issues you mentioned, even in extreme cold. I usually give it about 30 seconds for the afr's to settle...and that's if it wasn't running for a while. During the winter a minute and if it's frigid sub zero, 2-3 minutes. It's crazy how the afr's dance around when starting the car in -10F temps! The main thing is what you do after you start the car. Stay out of boost and keep the rpm's under 3500 with a light throttle. Let the car warm up properly through driving it, and that means oil temp. 10-15 minutes, or in my case, when my oil pressure settles to 40 psi at idle.
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Hope I'm not posting in a dead topic, but how about when it is ridiculously cold outside? I live in Northern Colorado and it was -24 (yes, NEGATIVE) this morning. Should I still only let it warm up for 30 seconds for the first start-up of the day?

 

I grew up where -30 was regular. You have a good oil, start and drive away. If you want the car warmer sooner you install a heater you plug in on a timer.

 

Also driving the car ups oil pressure which makes it safe.

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