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2018 2.5 premium Forester CVT
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We are thinking about stealth camping in west Texas. Would letting our 2018 Forester idle all night if we needed to sleep inside the car hurt the engine? Today’s cars have much better cooling systems than they used to.
 

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2019 Forester Sport Lineartronic® CVT
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Welcome!

"stealth camping" you say?


I've idled police cars all night long but never a POV like our Subaru, but I think it'd be OK. I did let wife and dog sit in my idling '01 Mercury GM in western Arizona for an afternoon while she slept in AC and I looked in old airplane museum, outside temp was 98-99.

Are you thinking of idling for AC … or … heat?
:nerd:
 

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2018 X3 M40i / 2016 X3 xDrive35i
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You bringing extra gasoline because idling all night is bound to get you stuck.. know more than a few folks that tried that and ran out of gasoline overnight
 

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1999 "L" - 231,000 mi. AT
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My son idled my '99 much of the night to stay warm two years ago. Didn't hurt it to my observation.

Obscure info dept - 5 yrs ago I researched how much fuel a car consumed when idling and ran across an EPA test document on same from ~1975. So would be carburated engines; I'd guess that fuel injected engines would not be any worse on fuel...

Idle fuel use varied with engine size, but for 2 - 2.5 liter engines it was 0.5 gal / hour.
 

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How much fuel does an idling engine use?


We'd have to guess at how much a 2.0 L turbo engine uses while idling, so given the numbers in the video, maybe 1-2 L per hour on the high side, and then if you are using the heater or a/c while idling, maybe a bit more. Given that the tank holds 60 L, maybe you'd be safe running the a/c all night, maybe not. Best to measure fuel flow while the a/c is running at idle.
 

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I'm something of a "safety nut." I wouldn't want to sleep in a vehicle that's just sitting there idling. Thinking of CO emissions and freak things happening.

Mike
 

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1999 "L" - 231,000 mi. AT
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How much fuel does an idling engine use?

Americans Have No Idea How Much Fuel Idling Uses - YouTube

We'd have to guess at how much a 2.0 L turbo engine uses while idling,
All welcome comments and data; this is what a forum is good for!
From the video clip at about 2 minutes, it says a 1.5 liter fuel injected engine uses 0.18 gallons/hr at idle.
So the 1975 EPA data of 0.5 gal/hr for a larger 4 cyl (carburated) engine seems re-enforced as on the high side; so a Forester is not going to run out of fuel after 8 hrs of idling (< 4 gal consumed).
 

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+1 To what DockingPilot said.

If leasing and giving it back after, sure.
If I was owning it for the long term, no chance.

The Subaru direct injection engines have carbn buildup issues from memory - I wonder how long hours idling would affect any build up.
 

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An engine at idle is not stressing.
If you drive by any motels at night on the way to the states from Alaska in winter, you will notice that every car outside is running so that they don't freeze solid overnight.
Those that are not, which are driven by the uninformed, will still be there until they get thawed out the next day.

It sounds like the OP @Imabmwnut wants to have AC to keep cool.

Provided there is adequate fuel and since the cooling system fan on a Subaru is electric (i.e. not a belt powered fan), the OP's car, and any car so equipped would be quite happy idling away until it runs out of gas. In the case of a diesel, it's even better because their fuel use at idle is very low..
Ever notice that the trucks are all running at a truck stop when it's hot or cold?

In hot environments, it will help a bit to keep the car's engine cooler if the hood is popped and left slightly open, since it doesn't have the benefit of air rushing through when driving, but that's just to be nice.

As far as CO... Subaru's produce nearly undetectable amounts of CO, so your risk of CO poisoning from your car in an open air camping environment is probably less than your chances of getting hit in the head by a meteor that crashes through the moonroof.

It will use fuel overnight, so there is a cost, but damage to anything other than your wallet is BS.
 

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As far as CO... Subaru's produce nearly undetectable amounts of CO, so your risk of CO poisoning from your car in an open air camping environment is probably less than your chances of getting hit in the head by a meteor that crashes through the moonroof.
With all due respect, I would love to see the data you've used to draw these conclusions.

Mike
 

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Get a warm tent, warm sleeping bags, dress warmly, and for the love of all that is holy, don't idle your car overnight. Not only is it wasteful for fuel for the sake of camping, but it will also impact the oil service life.

If you're worried about staying warm, then maybe pre-warm the car before bed, shut it off, and then bundle up.
 

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@CGumina - I think the OP is talking about staying cool with AC rather than staying warm with the heater.

@subatron -
Modern cars with catalytic converters reduce CO to nearly negligible levels at the tailpipe when properly maintained.
Think about how many cars are running at idle right next to you when you are in heavy traffic on the freeway.
There will be literally hundreds of times (if not thousands of times) more exhaust gas produced within a short distance from your car, and those CO levels will be far, far worse than a single car sitting at idle in a campground or out in the boonies in the open air.

I'd like to hear an explanation of how sitting still in traffic for hours isn't dangerous, but doing basically the same thing while camping is...

The primary problem with CO is if you run a car in an enclosed space like a garage, because the car will continually reduce the oxygen level by burning it through fuel combustion and the car will eventually start running rich due to the lack of O2, which will begin producing more CO than the converter can accommodate.

A much older vehicle, or one without a cat, or a generator which is generally not required to have cat converter, especially those running in an enclosed space are the more typical killers.

A modern Subaru, running by itself in a campground... I'd still bet on the meteor being the more exigent threat.
 

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@DragonSubie7

I don't think we're going to agree about this. If you had some empirical data backing up what you think is the case, I might change my mind.

Regardless, I can't see taking a chance with something like this, but like I said, I'm a safety nut. :smile2:

Mike
 

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@subatron - We can agree to disagree..
I have no interest in changing your mind, but apparently you wish to change the OP's mind, perhaps with good intention, but it doesn't appear to be a fact based opinion.
Maybe if you had some empirical data backing up what you think is the case, I might change my mind, but I think you will find that hard to obtain.

CO poisoning is no joke, but unless a modern vehicle is compromised by modification or damage, they just don't put out the CO that cars used to.
That is a fact easily obtained by a plethora of sources.
They will put out more if operated in enclosed spaces as I outlined, because the engine will be running rich due to O2 depletion.
That is another fact easily obtained.
That doesn't translate to a car running in the open at a campground as being a danger or everyone driving in heavy traffic on a calm day would be dead.

Even with an older car before cats were invented to affect the CO levels out of the tailpipe, it would still have taken an enclosure or exhaust damage/blockage which routed that exponentially higher CO content into the car before the passengers would be affected.

On an allegorical bent, water is dangerous.
It will kill you if you drink to much of it (look it up) and you will die if you fall in and don't get above the surface to breathe.
That doesn't mean it is inherently dangerous to drink it (in moderation) or to swim in it (provided you know how), and there is also very minimal risk that you will die from drinking or drowning from bottled water, although both situations are theoretically possible.

Just because something can be dangerous doesn't mean it is in all circumstances.

Myself, I would not consider letting my car run all night so the AC could be on, because it is a waste of fuel, not because of CO poisoning or car damage, because other than opinions, there is no evidence that either are likely to occur. If there were, I'd like to see it, but somehow that information is unavailable on the web. Must be a conspiracy...

If the weather was so hot that I needed AC at night to camp, I think I would stay home or maybe go somewhere with a higher altitude.
If I REALLY needed either heat or cooling, worry about running the engine to provide that would not be a concern, but that's a fact based opinion.
 
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