Auto Stop-Start: Enable/Disable?

I found a helpful (relatively recent - March 2017) description of the problem and the way it is being addressed: https://www.autocar.co.uk/car-news/new-cars/stop-start-long-term-impact-your-car-s-engine

When the engine starts, there’s a point before the two surfaces become separated by the oil film called the ‘boundary condition’, where the crankshaft is spinning, but there’s metal-to-metal contact between the bearing surfaces.

This is when most wear takes place. Fitting stop-start means the boundary condition (and metal-to-metal contact) could exist perhaps 500,000 times in the life of the engine instead of 50,000 and normal bearings would wear out long before that.

Two things prevent that happening. The first is that bearing manufacturers are developing new bearing material with greater self-lubricating properties to resist wear on start-up.

[snip]

The second is improvements in lubricating oils. A modern engine oil contains an additive package comprising a complex chemical cocktail.

With low-friction bearing and lubrication technology in place the potential threat to engine life by stop-start systems should theoretically be overcome. But the current technology is still relatively new and only time will tell whether every car manufacturer has got it right.
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The bottom line for me is that we definitely do know that additional wear-and-tear could result from the friction of 10 times as many starts over a vehicle's normal operating life, but only theoretically know that the two ways this is being addressed - better bearings and enhanced oils - should be able to compensate for it.

Is that good enough for you in your car, to leave it on all the time? That's a personal decision for each driver to make.
 
JJCT said:
Is this for a Beemer? Although it is quite a laugh when someone else drives it and they freak out when it switches off.
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Yup it is, I got my new baby on Saturday. That's why I'm pretty interested in this stuff now :)
 
Foxhound5366 said:
Yup it is, I got my new baby on Saturday. That's why I'm pretty interested in this stuff now :)
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Hey congrats what model? I'll definitely be asking them to do that, pity I was there 2 weeks ago.
 
JJCT said:
A M240i about 5 months ago, just never knew it could be changed. I'm phoning my BMW "genius" tomorrow.
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I don't know if it can in South Africa, but I read a story that BMW had authorized their dealers in America to do the change. All it requires is to toggle a 1 to a 0 in the car's software, so if your genius doesn't know ask to speak to the workshop instead lol.

Nice car by the way!!! One day when I'm big lol.
 
Foxhound5366 said:
The bottom line for me is that we definitely do know that additional wear-and-tear
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Of course. Turning the steering wheel left results in additional wear & tear too. Not an issue if it's within the limits of what it was engineered to do & certainly not a reason to look for straight roads.

Remember BMW introduced stop start in 2007. They have 10 years of real world failure rate data on this tech, so you're not the guinea pig.

Foxhound5366 said:
could result from the friction of 10 times as many starts
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Of the 500k starts 450k are hot starts. So not really comparable 1:1. In fact the entire system shouldn't even become active until the engine is up to normal operation temperature.

But yeah if it makes you happy then disable it.
 
Thanks for the permission Havoc, lol. Will be sure to let the workshop know I got your sign-off :p

As for your points, they're all valid. Who knows what BMWs failure data states? Do you have the numbers? Do you think they'd disclose it and trigger the biggest recall in history? Somehow I doubt that.

More likely they're still trying to engineer themselves out of the problem, and sell extensions to their motorplan to the rest.

Like that quote said, only time will tell.
 
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Some great insight into SS for the F30 here:

http://www.bimmerfest.com/forums/showthread.php?t=606503

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Foxhound5366 said:
I found a helpful (relatively recent - March 2017) description of the problem and the way it is being addressed: https://www.autocar.co.uk/car-news/new-cars/stop-start-long-term-impact-your-car-s-engine



The bottom line for me is that we definitely do know that additional wear-and-tear could result from the friction of 10 times as many starts over a vehicle's normal operating life, but only theoretically know that the two ways this is being addressed - better bearings and enhanced oils - should be able to compensate for it.

Is that good enough for you in your car, to leave it on all the time? That's a personal decision for each driver to make.
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Stop start traffic is way more damaging to the entire powertrain than having to start it up via auto stop/start. Almost all oil in the drivetrain need more frequent mandatory replacement (vs inspection at your annual service and replacement if required), like engine oil and filter smust be replaced every 6000km if "Repeatedly driving shorts distanse of less than 8 km (5 miles) in normal temperature " or "Extensive engine idling or low speed driving for long distances." Just think about, the number one thing you are trying to avoid is heat. Now you go and idle at the most inefficient revs of the engine creating the most heat, letting heat build up in the entire engine bay... But that is better than stop start? :rolleyes: There is a reason why EVERY SINGLE owners manual says once you start up the car don't just stand there and idle, drive the darn car.

Nevermind as pointed out that instead of normal starter spec'ed you get a starter that would have been used on a much larger engine, ie its hardly eating up cycles on the starter. And your drivetrain will already be up to temp with oil everywhere so why that is an issue who knows.
 
If your car has the feature it can reliably support it.

Considering regulations then you need to blame the treehuggers for the lack of power and catalytic converter in your car as well and might as well go ahead and remove those too.

Leave it on if it's there.
 
Foxhound5366 said:
You know there is friction when the engine's crank shaft turns, right? Most friction occurs at start up when the metal isn't fully lubricated or at operating temperature. Now in an auto stop/start car, you're not just starting a car once per journey, but ten or twenty times.
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But it's already at operating temperature...

That is the massive difference.

Also everything remains primed while in it's standby/wait state. It's not a full startup from cold as it would be first thing in the morning.

In fact it shouldn't stop at all if it's not at operating temp.
 
I hate that function on my Tiguan and I think having a car switch on and off that many times in traffic will cause significant wear and tear down the line.

I never use mine and will also say deactivate it if you can.
 
Very annoying feature. My older vehicle stays off but the newer one defaults to on each time you start the car
 
Sauron, do you personally drive with auto stop/start always enabled on your car?

Also, like that story I quoted points out, any time a car is switched off you get a boundary condition where metal rests against metal and has to overcome this friction during start-up. Whether the enhanced oils manage to provide sufficient lubrication to fully overcome the increased friction from 10x the number of start-ups is the entire discussion.

Regarding the point made about wear-and-tear from stop/go traffic, I'm not advocating permanently disabling SS. I am personally going to ask my dealer to at least let my car remember my last SS setting so that it can default to off when I turn my car on, and then I can choose to turn the system on when I feel it would be helpful.

FiestaST, that's an interesting thread. The last post was particularly interesting, with the guy complaining about how there is a high-pitched sound whenever SS is activated and it disappears with SS deactivated. Is that an example of a SS-related failure? Unfortunately we don't get the end of the story lol.
 
dlk001 said:
Doesn't bother me at all on my F83. I actually enjoy the sound of the engine restart,
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Would it bother you if you felt that excessively short stop/start cycles were placing undue friction (and therefore wear-and-tear) on your engine?
 
I wonder if Engineering Explained (YouTube channel) would do a video on this if we sent him some messages requesting this getting looked into. He might be able to say if there's a realistic expectation of significant reduction in engine life when using this feature.

He would also be unbiased, since he doesn't have a conflict of interest in selling you parts down the line.
 
Foxhound5366 said:
Would it bother you if you felt that excessively short stop/start cycles were placing undue friction (and therefore wear-and-tear) on your engine?
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Would it bother you if you felt that excessive idling was placing undue stress (and therefore wear and tear) on your engine?
 
In my A1 I leave it on because it's barely noticeable, I turn it off if my Mom is in the car as she doesn't like it.... Mine turns itself off in very slow stop start traffic anyways so that doesn't bother me either....

I used to turn it off in the Opel Adam - that 3cyl engine had a counter balancing crank that made the engine butter smooth, but on startup and on stop start it would wobble the entire car as most 3cyl engines do and made it rather unpleasant after a while...
 
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