Be Gentle On The Engine When Cold A Myth?

[Timewerx]

We may have heard this all, especially from motor oil ads and automotive books: "The greatest amount of engine wear occurs in the first few minutes of operation after a cold start." Not only that, aluminum pistons tend to have bigger clearance against cylinder walls when cold and when the walls are cold, you get more unburned fuel, that and more clearance = more blowby and chances of fuel getting into engine oil and diluting it for worse.

I take that warning at heart. Although I don't warm up the engine (spend some idle time after a cold start, I drive right away), I'm quite gentle on the throttle and avoid high revs until operating temperature is reached.

But I'm surprised that many, if not, most drivers around I see, don't mind and make harsh accelerations/revving high after cold start in the morning, maybe because they're running late for work. They do this even if there's no reason too like there's no traffic to get ahead of.

Their cars sound fine too so I'm beginning to suspect that it's just a myth.

[dervdave]

But I'm surprised that many, if not, most drivers around I see, don't mind and make harsh accelerations/revving high after cold start in the morning, maybe because they're running late for work. They do this even if there's no reason too like there's no traffic to get ahead of.

I`d probably do the same if it was a company car :)

[Mistermena]

I hate seeing people start up and then bang dowm the road as fast as the !Removed! thing will go! its dangerous for a start and I always feel sorry for the poor sod that buys the car after they've finished with it. I always start my car and let it idle for 10 sec (Longer in winter) and drive off steady and always let my Turbo cool down after work. Guess thats why my Polo has over 206k on the clock and still on the same engine/clutch/Turbo/gearbox ect! And its a driving school car!...

Btw its not a myth. Around 80% of engine wear can accure whilst the engine is cold. If the engine oil was tested on these cars v "Normal driven" (Not idiots driver) then this would confirm the engine wear.

[acetip]

I remember several years ago arriving at a VW dealership just as the offce staff were leaving of for lunch.

about 4 of them jumped into a new Golf standing on the forecourt, that i guess ws a demo car.the car sounded like it was driven flat out in each gear as it went up the road. that could have done no good whatsoever to that poor engine.

but then they would not be buying it.

Ive always taking fairly easy on my engines till its up to running temp,though that can take a lot longer on a diesel engine than a petrol one.

[Cyker]

Have there been any studies on whether this is an urban myth or not?

I know there have been arguments about the oil being cold and thick, but modern oils are runny as heck even at low temps, and then there is stuff like magnatec which supposedly stays stuck to the surfaces more.

As for thermal expansion, I would have thought engines will be tighter when cold, not looser?

I used to drive my Yaris ultra gently when cold but in winter I find this just means it takes forever to warm up; I could literally get halfway to work before the cold indicator went out.

I don't bother with idling it for a while before I move off as I realised that I was just wasting fuel and not really warming up the car at all; I just go and drive like normal and the car reaches operating temp much faster.

The only concession I make is I try not to spin the turbo up, and I always let the engine idle when I arrive to give it a chance to cool off if it's been used as I know too many people who've had turbo failures by not doing that!

[cabcurtains]

With todays engineering tolerances the chances are it would take quite a long time to actually see the effect of the damage, a friend of mine drives his cars to death and has never once had an engine related issue. For him its just money wasted on additional brakes and tyres etc etc

Its people driving around with low oil levels that do the most damage. Cold oil is better than no oil.

Also if anyone has ever watched the way cars get driven around the docks i.e on the limiter in 1st gear when cold and brand new, you can see they can take it

[Karma Supra]

It's not an urban myth, as said above; engines are designed to work within certain temperature ranges. - for example when rebuilding my old supra engine I needed to warm the pistons to near 80 degrees to remove the con rods, Below there they are solid and immovable.

Oil also doesnt flow properly at lower temperatures, although modern synthetic oils flow better when cold and remain consistent.

In the M3 when it is cold there are orange lights that "extend" the redline down to 4Krpm. As the engine warms the lights go out, so you know you can rev higher.

One think that does vary depending on manufacturer advise is, starting up and leaving to idle, or starting up to gentry drive away, BMW actually specify that you should start and gently drive off immediately.

It's not just the engine though either, I'd not want to go mad on a cold transmission.

[PaulinhoT]

I always warm my car up, mainly in the sense that I take it easy, drive a few miles for the temps to come up

[Mistermena]

Have there been any studies on whether this is an urban myth or not?

I know there have been arguments about the oil being cold and thick, but modern oils are runny as heck even at low temps, and then there is stuff like magnatec which supposedly stays stuck to the surfaces more.

As for thermal expansion, I would have thought engines will be tighter when cold, not looser?

I used to drive my Yaris ultra gently when cold but in winter I find this just means it takes forever to warm up; I could literally get halfway to work before the cold indicator went out.

I don't bother with idling it for a while before I move off as I realised that I was just wasting fuel and not really warming up the car at all; I just go and drive like normal and the car reaches operating temp much faster.

The only concession I make is I try not to spin the turbo up, and I always let the engine idle when I arrive to give it a chance to cool off if it's been used as I know too many people who've had turbo failures by not doing that!

I think you'll find that Castrol magnatec advertising campain (Years ago) was to show that most of the engine wear was done on start up and hence this oil tech stuff! I (As a driving instructor for over 19 years now) always teach my pupils to(When they get there own car and its cold start) start the car up and just let it idle for 10 seconds and drive off in a normal manor. If you ever have the bonnet open and start the car you'll hear that it take a few seconds (More so with a semi synth oil than a full synth) for the oil pressure to build up at the cams (Where most pressure is) so driving off to soon puts load on the lube system that just doesn't need to happen. And as said you dont want to be putting extra load on a cold trans!...

If you take a Google search for "The engine oil Bible" you'll see that just by letting the engine idle could give you and extra 100k miles of life to your engine. I rest my case me lord.

[Mistermena]

I remember several years ago arriving at a VW dealership just as the offce staff were leaving of for lunch.

about 4 of them jumped into a new Golf standing on the forecourt, that i guess ws a demo car.the car sounded like it was driven flat out in each gear as it went up the road. that could have done no good whatsoever to that poor engine.

but then they would not be buying it.

Ive always taking fairly easy on my engines till its up to running temp,though that can take a lot longer on a diesel engine than a petrol one.

I remember buying a brand new Citroen ZX diesel years ago for my School and the guy the other side of the compound razzed the hell out of it when I took delivery of the car. So I razzed the hell out of his face when he got out of the car! I wasn't a happy bunny that day I can tell you!

But I'm a calm and reformed person now. Lol

[Mistermena]

With todays engineering tolerances the chances are it would take quite a long time to actually see the effect of the damage, a friend of mine drives his cars to death and has never once had an engine related issue. For him its just money wasted on additional brakes and tyres etc etc

Its people driving around with low oil levels that do the most damage. Cold oil is better than no oil.

Also if anyone has ever watched the way cars get driven around the docks i.e on the limiter in 1st gear when cold and brand new, you can see they can take it

Now then, thats all to true about low engine oil levels. Why some people wait till the oil warning light comes on b4 they check it is beyound me. I check mine every morning befor I start the old girl up. It just takes seconds to do and could save thousands of £ in the long run.

[Timewerx]

Thanks for all the response!

I only idle for 10 seconds from a cold start but not any longer since too much idling will result to increased carbon deposits which is also bad.

I live at a place where you have to go up a steep road after going out the drive way, I don't mind going just 10 kph to treat the engine gently as it warms up. Nearly all neighbors except for me and an old couple, drives 50 kph up this steep road after starting their cars! I could hear them rev their engines above 4K rpm!!