Save Money & Time: Drive Your Vehicle, Not Idle!

[Cyrus]

I got this in my school FYI email:

Idling is not an effective way to warm up your vehicle, even in cold weather. The best way to do this is to drive the vehicle. With today's modern engines, you need no more than 30 seconds of idling on winter days before driving away. In fact, idling an engine for two minutes uses about the same amount of fuel it takes to go about one mile. So, you can save money, emissions, and time if you just get in and go!

I think my engine and transmission oil needs more time than that to heat up and work properly. Also, suddenly driving off with a cold engine block is a good way to develop cracks in the cylinder walls - which is why you don't just pull the throttle all the way out on an airplane. You gradually reduce it back to idle.

Brewski, give me your expert advice.

 

[Jame]

Warming up the engine block will take a lot longer than 2 minutes if you're just idling, it is quiet a lot of metal. Also the difference between idling and driving of carefully is not that big. I don't idle but drive gently in the first 10 minutes and haven't ever experienced any cracked cylinder walls, despite some less gently driving after 10 minutes passed.

 

[LucasJ]

30 seconds doesn't seem like a long enough time. A guy I know fixes cars for a living, and since the weather turned bitter up here (-20s at night) they've seen an influx if cars with power steering problems caused by, in his opinion, not letting the car warm up long enough. Same thing happened to me last winter.

 

[Gokul43201]

30 seconds is just about long enough to run the engine oil through the system, I guess. My owner's manual (Honda Accord) suggested something along the lines of waiting 20-30s, and drive "gently" for the first 5 minutes, if I recall correctly. That's what I've always done.

I've had this car for 6 years (in the mid-west and NE), and never once idled for a minute before taking off. So far, not a single problem with the engine, and I still get over 30mpg from a car with 160K miles on it.

 

[Ivan Seeking]

30 seconds is just about long enough to run the engine oil through the system, I guess. My owner's manual (Honda Accord) suggested something along the lines of waiting 20-30s, and drive "gently" for the first 5 minutes, if I recall correctly. That's what I've always done.

The problem that we have is that our driveway is fairly steep and long, so there is no way to avoid loading the engine.

I've had this car for 6 years (in the mid-west and NE), and never once idled for a minute before taking off. So far, not a single problem with the engine, and I still get over 30mpg from a car with 160K miles on it.

The real test is whether you get 180k or 300k out of a Honda.

 

[turbo]

With a push-rod type engine, I always let the engine idle until the lifters are pumped up (tapping noise stops), then drive away gently. Never any problems, and my cars routinely last 200K miles or so, though the road-salt eats up the bodies before I can wear them out mechanically, so I'll never know what the engine/transmission will last. I sold my last Pathfinder (lightly used) at the age of 17 years with about 190K on the odometer. The buyer did extensive body work, and two years later, he was still driving it.

 

[mgb_phys]

If you have a modern engine management system it will do this for you.
My subaru annoyingly revs to about 3500 for a couple of seconds about 10secs after I start if it is idling - I think it is monitoring the NOx in the exhaust and trying to get the combustion up to temperature.
Trouble is this is just when I'm under my neighbors window - she thinks I'm doing it to annoy her!

 

[hypatia]

My auto manual also says not to idle more then a minute. But I need heat, so I warm it up just a tad, say 5 minutes. Just so my heater is kicking out a bit of warmth.

 

[Averagesupernova]

I would say it is more about the ability of the oil to do it's job. A cold engine always wears more than a warm one. I lean towards letting it warm up at an idle.

 

[brewnog]

Ha, my "expert advice" would be that 30 seconds is more than adequate. I get in and drive away, unless the car needs de-icing (in which case I let the engine run, with all the lights and demisters on, and that's more to try and get heat into the cockpit!).

However, you should then drive the car gently (avoid full throttle, and limit your revs) until the water is showing a reasonable temperature. I wait until the water temperature is at around 60°C before giving it stick, and 80°C before thrashing it.

Far more damage is done by thrashing a cold engine than by not idling an engine at all, and then driving normally.

The car I have at the moment never gets warm if you only let it idle, it has to be driven to get any heat into the thing. While it's idling away after starting, the oil is cold, the oil pressure is low, and it's constantly wearing away bits of metal.

Ivan, unless you blat up your drive at 70mph, I wouldn't worry about loading the engine excessively before it's warm.

 

[Ivan Seeking]

Ivan, unless you blat up your drive at 70mph, I wouldn't worry about loading the engine excessively before it's warm.

In that case I'm probably okay... but Tsu is another story... esp with her V6 Solara.

 

[physics girl phd]

But I need heat...

Yes! That's my reason too!

 

[dlgoff]

So, you can save money, emissions, and time if you just get in and go!

Doesn't seem they are worried about your saving your engine. Maybe you should reply and ask if they are willing to repair your engine when it dies.

 

[Gokul43201]

Doesn't seem they are worried about your saving your engine. Maybe you should reply and ask if they are willing to repair your engine when it dies.

From what folks are saying so far, it seems you don't do much harm to your engine.

Clearly you save time, but I doubt you save much money or emissions. I would imagine you'd get a significantly lower mileage over the first few miles driven with a cold engine (compared to when it's warmed up). But that's just a guess - I have no idea what the numbers would be.

 

[wolram]

I think air cooled engines (aircraft) are a different kettle of fish, fast heating and cooling can cause cracks, look to the vw engine, finding a twin port head with no cracks is a rarity.

 

[turbo]

I think air cooled engines (aircraft) are a different kettle of fish, fast heating and cooling can cause cracks, look to the vw engine, finding a twin port head with no cracks is a rarity.

Part of that syndrome may be due to the fact that the VW bug with the weight over the driven wheels was great in snow, and was abused in some pretty severe climates.

 

[wolram]

Part of that syndrome may be due to the fact that the VW bug with the weight over the driven wheels was great in snow, and was abused in some pretty severe climates.

I have rebuilt hundreds of these engines, the only time i have come across one without cracks in the cylinder heads, the owners have allowed the engine to warm up and cool down slowly, plus i would not guarantee the engine unless the heads were re torqued, i used to run an engine for an hour and re torqued the heads, it was up to the owner to get them re done before 500 miles.

 

[JasonRox]

The most I've ever waited to start driving my car is about 3 seconds. I drive hard too.

I have to wait 2 to 3 minutes before I start riding my scooter though, and I have to wait 2 to 3 minutes before killing the engine too.

 

[Cyrus]

The most I've ever waited to start driving my car is about 3 seconds. I drive hard too.

I have to wait 2 to 3 minutes before I start riding my scooter though, and I have to wait 2 to 3 minutes before killing the engine too.

Note to self: Don't buy used cars from Jason.

 

[Ivan Seeking]

Note to self: Don't buy used cars from Jason.

Go to this guy [profanity]
https://www.youtube.com/watch?v=uTvwwDnrQL8

 

[Cyrus]

Did this actually go on tv?

 

[Ivan Seeking]

Did this actually go on tv?

Back in those days, those spots were usually live, so I would imagine that it did.

 

[brewnog]

Conversely, I'm always careful to let me engine cool down sufficiently before turning it off. If the turbo is still spinning at any great rate when the engine is killed, oil pressure disappears and the bearings get scuffed. Also, if the oil and running components haven't had chance to cool, the oil can get 'baked' on, causing nasty deposits and sometimes even blocking oilways.

 

[Ivan Seeking]

How would you define "sufficiently" for non-turbo engines?

 

[brewnog]

How would you define "sufficiently" for non-turbo engines?

If you have an oil temperature gauge, I'd wait until that's settled to with 5-10 degrees of the water temperature. If not, just don't switch it off if you've just pulled off the motorway, give it 5 minutes of gentle (around town) driving or idling before switching off.