Idling for several minutes before driving off in cold weather... why? (1 Viewer)

[Holadem]

Why, to warm up the car, stupid!

That's what I am told by everyone anyway, right before they hand me their Stupid Question of the Year Award.

Just wondering if there was any factual basis for this practice - it wouldn't be the first time people are doing something because everyone else does it.

EDIT: OK wrong forum, ma bad...

--
H

 

[Mike~Sileck]

I smell a forum move. Personally I start the car quickly, turn on the heat, and then go back inside for 10 minutes on cold days. Why? So the car is warm for my cold butt!! Makes sense from an engineering point of view though, I mean parts that are a little warm are likely better to perform well than metal thats been freezing for awhile. Then again, you could be right and there could be no reason for it. Regardless of the engine though, I'll continue to turn my heat on .

Mike

 

[John Miles]

Best to let it warm up only a minute or two, then drive away with a light foot on the gas until the oil temp comes up.

If you just let the engine idle for long periods in the morning and then drive off normally, you're (a) risking carbon buildup in the engine; and (b) stressing the parts of the car that didn't get warmed up, from the transmission to the tires.

 

[Malcolm R]

Most manuals in newer cars say this is unnecessary. The car will heat up faster while being driven, and all the gas you burn while standing still is just a waste. I just start and go, and my new CRV is already blowing heat before I'm 1/4-mile down the street.

I think the practice endures because of "the old ways" handed down from generation to generation. I know my parents have always "warmed up" their cars, so their practice threatened to rub off on me. I've also successfully resisted adopting my father's practice of "revving" the engine several times right after it starts up. It's fuel injected, Dad. You don't need to do that!

And, as mentioned, some people are just wusses who can't endure 10 minutes in a chilly car.

 

[Kwang Suh]

IIRC, it's those primitive things called carburators that needed to get warmed up. Since everything is fuel injected now, warming up is just a waste of time and fuel.

 

[Keith Mickunas]

I thought it was still ideal to let the car get to the point where it drops the idle down to the normal speed. I believe it's all related to the oil temperature, when it's too cold it's not circulating in the engine properly and not doing a good job of protecting the engine components.

 

[Philip_G]

Idling isn't good on an engine. It is my opinion that driving gently for a few miles warms the car up quicker and exposes it to less wear.

do I have proof? no

 

[Steve Schaffer]

Precisely, in days of yore cars flat wouldn't run very well when cold--they coughed, sputtered, hesitated, etc. This actually got much worse in the early days when emmission controls were added but before Electronic Fuel Injection became common.

Another big factor was that engine oil was not as sophisticated as today. It actually had to warm up a while before it would thin out enough to circulated around the engine properly.

These days we want the engine to warm up as quickly as possible so it will go into "closed loop" (when cat is warm enough to become effective--catalytic converters don't work when cold). For this reason cold idle speeds are creeping up again and we are encouraged to minimize warmup time and just start and drive gently until the temp comes up a bit.

It should be noted that oil takes much longer to reach normal operating temp than coolant. In other words just because the temp guage is up to normal does not mean the oil is hot enough for impurities, especially moisture, to boil out. This is why more frequent oil changes are recommended for those who do mostly short trip driving. It may only take a few blocks for the temp guage to read normal operating temp but the oil needs maybe 5 or 10 miles. This is also why mfgs are now recommending 5w-30 and even 5w-20 oil instead of 10w-30 or 10w-40.

One can safely drive "normally" sooner with the lighter weight oils, they circulate better at lower temps and the full and semi-synthetics are still good for high temp operation in the summer months.

 

[Philip_G]

Guess it depends on the car and the age, but closed loop usually just means the ECU is dumping pre-set amounts of fuel into the engine and ignoring the various. Guess newer 4 wire sensors provide valid data a lot quicker than the old single wire.

 

[Leila Dougan]

My car is only 6 years old but if I don't leave it running for 2-3 min before driving off, it'll stall. Obviously something is wrong with it since it's only started this behavior in the last 2 years or so, but I find 2-3 min of idling to be just fine.

 

[Caleb Penner]

I guess you should tell all the truck drivers at the truck stops... Most truckers leave their rigs on all the time, except for refuelling. At my summer job, I drove a pick-up which was left on all day. Diesels can idle until the fuel runs out. But yeah, I agree with your opinion.

I sometimes idle after a cold start with the fan on high and defrost. If I can't see out of the windshield, it's dangerous to drive.

 

[Jason Hughes]

The reason I do it in the winter is because I am lazy. Since my condo does not have a garage or a carport, I have ice and/or snow on the car in the winter, which, ofcourse, needs to be brushed or scraped off. Homey don't play that game! In other words, I let the car "warm up" for 10-20 minutes so everything melts.

The fact the car is hot inside the instant I get into it doesn't hurt either.

 

[Philip_G]

And obviously diesel engines operate slightly differently than gasoline.
I've seen stories on truckstops that have some sort of cold air and power tube that they run to the cab of the truck to provide AC power and A/C while they're resting, much cheaper than idling it.

and here's a link http://oee.nrcan.gc.ca/idling/tool_kit/d15_e.cfm?Text=N

 

[Marko Berg]

Haven't you people heard of engine block and/or electric passenger cabin heaters? They make so much more sense than leaving the the car idling.

 

[JustinCleveland]

And I did an interview with AAA Wisconsin last week where an expert said that exact same thing. Basically said warming up isn't needed anymore, and hasn't been for decades.

 

[Todd Hochard]

Beyond about 30-40 seconds, to ensure the top end of the engine is being oiled (and yes, it does take that long for some to get oil from the pan up there), there is really no benefit.
Exactly. (And, I used to live in Maine, so spare me the "you wouldn't know." )

 

[Philip_G]

I've lived in ND where a car would have to idle for over an hour to get any heat to the cabin when it's -30F
People just left it running there a lot it seemed like.

 

[Drew Bethel]

To summarize, here are the things to do that make the most sense:

- start your car and let it sit for a minute or two. I think most would agree that the most wear and tear occurs when you first start up. So it's logical to give the engine a little bit of time to get the fluids in motion.

- buy an engine heater. Maybe I will do this, especially living in Minnesota!

- Drive gently for the first few 10ths of a mile. Makes sense regardles of the weather.

 

[DonRoeber]

I mostly start mine early to let the defroster clear the windshield, rather than having to scrape it off myself.

 

[Chris Lockwood]

I know people that do a variation of this when it's hot outside- start the car, crank the A/C, and wait outside a few minutes while the inside of the car cools down.