Leaving an engine running?

Geez Louise · 24-05-2010, 10:31 AM

My next door neighbour has purchased a 2004 model car and insists every morning on leaving the car running for at least 5 mins before driving it.

I spoke to his wife this morning and she told me that the dealer they bought the car from told them to do this as it is better for the engine in the long run.

What is the benefit of doing this? 5 mins seems a long time to leave a car running in a stationary position. I know with older model diesel cars you need to run them for a bit before driving them, but I didn't think it was necessary for newer cars.

RG · 24-05-2010, 10:34 AM

No need for something of that age.

They're designed to be able to just start and go, it isn't the 60's anymore.

T3man · 24-05-2010, 10:35 AM

The dealer is trying to cultivate future business. When the engine is glazed over and starts using oil excessively after about 100,000km he will be able to "sell" the customer a rebuild. Good business acumen if the customer is an idiot and knows no better.

LTDHO · 24-05-2010, 01:34 PM

Quote:

Originally Posted by T3man

The dealer is trying to cultivate future business. When the engine is glazed over and starts using oil excessively after about 100,000km he will be able to "sell" the customer a rebuild. Good business acumen if the customer is an idiot and knows no better.

I thought the same thing

Peter B - CV8 · 24-05-2010, 01:42 PM

Tell them to read the owners manual & then get the dealer to explain why he is going against company policy..... and commonsense.

JimNiki · 24-05-2010, 10:59 AM

All motors wear in the first few revolutions while oil poressure is established.
Motors also wear faster when cold.
As long as you don't thrash it for the first minute or 2 whilst driving off, then you're really gaining nothing other than wasting fuel.

just my 2c {+gst****

**Raptor** · 24-05-2010, 11:07 AM

As RG says, it isn't the 60's anymore.

It was fairly standard practice once upon a time to allow things to warm up and so the car wouldn't stumble too much before you could push the choke in, but a 2004 car

I don't think so

tex · 24-05-2010, 11:08 AM

great idea of your neighbours - crank that heater up!

I run my cars this time of year for maybe that long each morning - nothing to do with warming the engine - it's to defrost the the interior! -2 deg this moring! -6 yesturday!

Just spoke a a guy at Lianawine (central Tas) and it was -10.8 overnight. Brrrrrrrr.

Rodp · 24-05-2010, 11:09 AM

If he wants glazed bores then he's going about it the right way.

No need for a 5 minute startup. I pretty much turn the key and go, but no WOT until the engine has reached optimum temp.

Mr Hardware · 24-05-2010, 11:15 AM

my understanding is most engine wear occurs whilst cold, so the trick is go get them up to operating temperature as quickly as possible without hurting them in the process. ie turn it on and drive gently

Boosh Brus · 24-05-2010, 11:18 AM

The BMW M cars have tachos with little LED indicators that show the maximum recommended rev range for the engines temperature. I thought that was pretty cool when I first saw it.

ryanstev · 24-05-2010, 12:12 PM

It's better to warm an engine up by driving it, it warms up the other parts, such as transmission and diff for one thing, but you also have higher oil pressure when you're driving than idle.

Bad Bird · 24-05-2010, 12:16 PM

It sounds like a good way to get hot-spots in your head/heads to me...

jpd80 · 24-05-2010, 12:35 PM

Most newer cars are designed to get up to running temperature very quickly.
I only have to drive my FG for about 2 klm and the temp gauge is moving....

DBourne · 24-05-2010, 01:05 PM

I let my car go through it's "auto-choke" when I first fire it up, takes close to a minute, then I just leave it for another 30 seconds n take off slowly

Jim Goose · 24-05-2010, 01:16 PM

I have seen people during winter rev the freckle out of a cold engine as soon as it starts..... which is umm, not a good thing.

5 mins is over the top.

In really cold temperatures once the needle moved I would be off, usually 2 mins at most?

I have a 30m driveway so by the time i open the gate and close it, its warm enough.

Melz · 24-05-2010, 01:20 PM

I still warm up my old cars, not for 5 mins though... As for the newer. I turn it on, do the whole adjusting the mirrors, seat, scratch my head, etc routine then go... Don't find the need to 'warm it up'.... but then I don't find the need to give it a flogging as soon as I start driving it!

mik · 24-05-2010, 01:53 PM

run 20 seconds to let oil circulate through then off i go , nice and gentle, 2000/2200 revs max till operateing temp.

mrbaxr6t · 24-05-2010, 02:38 PM

on my focus XR5 temp seems to be relative to where its measured it has water and oil temps and oil pressure gauges when you start it and its brutally cold say 3 degc it almost instantly winds the oil pressure needle right off the dial it slams 5 bar (the upper limit of gauge very quickly) maybe 4 seconds its there so its pressuring the oil up real damn fast then you begin to drive and in maybe 3 minutes heat starts to come from the heater and maybe another 3 or 4 after that the temp rises BUT what is interesting is the oiltemp still hasn't moved from absolute zero and the pressure remains at maximum of the gauge or very close to it, it takes a further 10 minutes or more of driving for the oiltemp to come up and as it does the pressure goes down due to reduced viscosity I would think, so I think the watertemp gauge is good but oiltemp is a better indicator of engine temp and they take much longer to warm through than it appears.

jpd80 · 24-05-2010, 04:26 PM

Quote:

Originally Posted by mrbaxr6t

on my focus XR5 temp seems to be relative to where its measured it has water and oil temps and oil pressure gauges when you start it and its brutally cold say 3 degc it almost instantly winds the oil pressure needle right off the dial it slams 5 bar (the upper limit of gauge very quickly) maybe 4 seconds its there so its pressuring the oil up real damn fast then you begin to drive and in maybe 3 minutes heat starts to come from the heater and maybe another 3 or 4 after that the temp rises BUT what is interesting is the oiltemp still hasn't moved from absolute zero and the pressure remains at maximum of the gauge or very close to it, it takes a further 10 minutes or more of driving for the oiltemp to come up and as it does the pressure goes down due to reduced viscosity I would think, so I think the watertemp gauge is good but oiltemp is a better indicator of engine temp and they take much longer to warm through than it appears.

Water temp indicates when the cylinder case and heads are at operating temperature,
that's where the majority of engine wear occurs during engine warm up but you're right,
oil temperature indicates when the whole engine is fully warmed up.

The drop in oil pressure is probably viscosity change but it could also be
the clearances opening up a little in bearings and pump as metal expands...

Geez Louise · 24-05-2010, 02:50 PM

I didnt think it was a necessary process anymore. It is so annoying...every morning...same time, for the same amount of time. My bedroom wall is right next to his driveway. At least I have a morning alarm.

regular as clockwork.

Thanks for the replies.

greens_tuf · 24-05-2010, 03:32 PM

The owners manual of my Golf VR6 says that when cold you should just start and drive at low rpm, no need to let it idle...

** I don't remember the exact wording, but it was something along those lines...

Mz Revvv Head · 24-05-2010, 03:40 PM

I also didn't think with the newer cars you had to warm them up ...
5 minutes seems a very long time to me ...
Altho with my XR I let it warm up for a minute or 2 ..

I've been told when I pick up the GT-P, I have to warm it up ???
Due to the very thick oil it has in it ?
And I was also told the GT'S don't run well when it's cold for that reason ???
Any advice would be great ... ty

**Tucool** · 24-05-2010, 04:33 PM

slightly off topic, but where I had some minor warranty work done they had a practice of starting all the cars in the lot and leaving them idle for 20mins twice a week !!! it sent shivers down my spine.

jpd80 · 24-05-2010, 04:45 PM

Quote:

Originally Posted by Tucool

slightly off topic, but where I had some minor warranty work done they had a practice of starting all the cars in the lot and leaving them idle for 20mins twice a week !!! it sent shivers down my spine.

It's not a problem leaving a petrol engine to engine idle for 20 minutes, you will not glaze bores.
Once it's warmed up, it's no different to a normal car sitting stationary with the A/C on.....
It's needed to ensure the batteries remain fully charged, there's some parasitic loss with modern electronics.
Every dealer I know does this and has done it for years, the lack of prolific glazed bore problem says
that the thought of significant blow by occurring with low tension rings at idle is minimal...

I think the glazed bores idea came from Diesel engines, they don't like to idle without load,
that will eventually glaze the bores

lofty · 25-05-2010, 03:29 PM

Quote:

Originally Posted by jpd80

I think the glazed bores idea came from Diesel engines, they don't like to idle without load,
that will eventually glaze the bores

I wish someone would tell that to all the truck & van drivers that refuse to turn off their motors while doing deliveries etc.

mik · 25-05-2010, 03:41 PM

Quote:

Originally Posted by lofty

I wish someone would tell that to all the truck & van drivers that refuse to turn off their motors while doing deliveries etc.

some turbo engines need to idle down before shutting down(more commonly big diesels).

jpd80 · 25-05-2010, 04:51 PM

Quote:

Originally Posted by lofty

I wish someone would tell that to all the truck & van drivers that refuse to turn off their motors while doing deliveries etc.

That's more to do with diesel generator sets, when the diesels run without
any load for extended time, they tend to flash burn the bores causing glazing...

SVTVNM · 24-05-2010, 04:48 PM

My old man still gets in his late model Pajero diesel and sits in it for what seems like eternity before he drives off. I used to drive a 85' Diesel Hiace for about 6 years over 500,00klm I put on it, drove it everyday not once sat in it to warm it up just started it and drove off sensibly, Thats always been my opinion just dont flog a cold engine.

jpd80 · 24-05-2010, 04:59 PM

Quote:

Originally Posted by SVTVNM

My old man still gets in his late model Pajero diesel and sits in it for what seems like eternity before he drives off. I used to drive a 85' Diesel Hiace for about 6 years over 500,00klm I put on it, drove it everyday not once sat in it to warm it up just started it and drove off sensibly, Thats always been my opinion just dont flog a cold engine.

Well said and most people do similar.