Warming The Car Up In Idle Is Bad For The Engine

[Johan007]

After warming the engine for a minute on icey roads my old man pointed out that in his book (Avensis) it says the car should be driven straight away and not left to warm up (or down) by idling. Looking on the internet for answers it says the rich fuel mixture is not good for engine...

Idling an engine is bad in so many ways. The fuel is not completely burnt, so it condenses in drops on the cylinder walls. This leads to both extra wear of the cylinder walls (because the fuel washes the lubricating oil off the walls), and unburnt fuel flowing down the walls and contaminating the oil in the sump. Idling also drops the temperature of the spark plugs, leading to dirty plugs, which can worsen your fuel consumption by some 5%.

•An idling engine releases twice as many exhaust fumes than a vehicle in motion.

•If every driver in Canada avoided idling for 5 minutes a day, we could prevent 1.6 million tonnes of carbon dioxide from being emitted.

•No more than 30 seconds of idling is needed for oil to circulate through your engine. Many components, such as the wheel bearings, tires and suspension system will only warm up once the vehicle is moving.

•Restarting your car many times has little impact on engine components, adding only around $10 per year to the cost of driving, money that is recovered in fuel savings.

•Ten seconds of idling uses more fuel than restarting the engine.

•Idling can damage your engine since it is not operating at its peak temperature where fuel is completely burned. Fuel residue from incomplete burning can damage engine parts.

•Idling a vehicle for 10 minutes a day uses an average of 100 litres of gas a year. If gas costs 70 cents a litre, you will save $70 per year, just by turning your key.

•During the winter, Canadians idle their vehicles for a combined total of 75 million minutes/day. This is equal to a vehicle idling for 144 years. Although we idle our vehicles about 40% less in summer, we still waste an enormous amount of fuel and money.

•A block heater warms the oil and engine coolant, making it easier to start your vehicle and improving winter fuel economy by as much as 10%.

So, idling is bad for your engine, bad for your health, and bad for the environment.

[OldSkoO1]

warming up is pretty pointless for more than the time it takes to put on your seatbelt

however idling after driving at speeds > 30mph is recommended, even by toyota in the manual on turbo diesels.

I always let my t180 idle for between 20 and 40 seconds depending on my driving.

[DominicPriestley]

I think the general idea on here is that a short warm up, less than 30 seconds to get oil round is good. Then, not pushing the revs and engine too hard until it is up to temperature i.e stabelised in the middle of the temperature gauge is good. Also a period of time 30-60 secs to stabilse temperatures before turning off is also good. I dont think many people will warm the car for too long at Idle.

[eiriksmil]

I think the general idea on here is that a short warm up, less than 30 seconds to get oil round is good. Then, not pushing the revs and engine too hard until it is up to temperature i.e stabelised in the middle of the temperature gauge is good. Also a period of time 30-60 secs to stabilse temperatures before turning off is also good. I dont think many people will warm the car for too long at Idle.

Don't only consider water temperature, but also oil temperature. I never beat on my car cold, if I'm going to drive hard I usually let the tyres and the oil warm up. Circulation takes 30 seconds, but it won't get the oil up to a good running temperature. Cool-off time on N/A cars is not so important, the point of letting a turbo-charged car cool down is for the turbocharger, not the engine.

Pretty interesting numbers on idling there, by the way ;)