[Mech Spec]

Unless some mad max shit happens im never driving a car that many miles so IDK why we are talking about the effects of a feature on the condition of the engine far outside the period of original ownership.

The link below says most vehicles are in the junk yard before they reach 186k miles.

https://autorecyclingworld.com/what-...le-in-the-usa/

It would take me 26 years of only driving 1 car to reach that mileage. If you drive significantly more miles you probably don't engage the start/stop very often because you are on the highway all the time.

[W2k]

Originally Posted by NSXR

The claim is that additional start/stops do not increase appreciable wear. Imagine Nike said something utterly stupid like additional steps do not increase appreciable wear on your shoes.

Originally Posted by ZL9M2

The start/stop function obviously causes more wear on the starter. Source = common sense.

The problem with this "common sense" argument is that it's overly simplistic and ignores engineering realities.

Yes, if you take a machine that was designed to live for a certain number of cycles and you run it twice as often, it will wear out twice as fast. Sure.

However, and this is the important part, if the "certain number of cycles" is so high that even at a much higher rate of use you will realistically never reach it, then it does not matter in the slightest.

Starters intended to be used in auto start/stop systems are not identical to old school ones. They and the engines they're mounted to were built to a different set of requirements. They will not fail any faster, indeed most will not fail before the whole car is headed to the junkyard.

If your Nike shoes were designed to last for five billion trillion steps (I made that number up, please don't fact check me) and you walk 10,000 steps per day, then you will not see any increased wear from walking 20,000 steps instead, because you will be long dead before the shoes wear out at that rate. See what I mean?

[Efthreeoh]

Originally Posted by ZL9M2

The start/stop function obviously causes more wear on the starter. Source = common sense. If it didn't then starters would last forever.

But if you read the engineering literature, starter motors for ASS systems are beefed up to handle the increased engine start events. Also, some ASS designs fire cylinders early to reduce the load on the starter motor.

Additionally, a warm or hot engine starts much easier and stresses the starter less because the cylinder is hot and fuel vaporizes faster and the oil is hot, which reduces cold oil drag.

[BWBike]

I find it annoying and always turn it off as soon as I start the car.

I came from the days where I had junker cars that if you came to a stop the car would sometimes stall (a bad thing). Sometimes it was difficult to restart the car.

Yeah, new cars are way better, but I can’t get rid of that nagging thought that an engine shutting off at a stop sign is not good.

[TheWatchGuy]

The greatest thing ever to come from the chip shortage a couple years back, was my truck came with auto stop/start deleted because they didnt have the parts.

good riddance

[NSXR]

Originally Posted by W2k

The problem with this "common sense" argument is that it's overly simplistic and ignores engineering realities.

The starter was never a concern for me, it's the cylinder walls, and piston rings, which are largely identical to those from past decades, and will in fact wear out 10 times as fast if you use them 10 times as much. As I said earlier, there are expensive exceptions, but those come at a cost as well, and are relatively rare.

I think for first owners the start/stop isn't a problem, but for the 2nd and 3rd owners there will be issues. The phrase "they just don't make 'em like they used to" will be ever increasingly used at Autozone, and neither the first owner, nor the manufacturer will even blink.

I expect technology to move a half-step forward at at time, not one step forward and two steps back. This is a problem with me, not the system that's designed to bleed us dry.

[KevinC]

[ppointer]

Originally Posted by NSXR

This is incorrect.

The increased wear is on the cylinder walls because of a momentary lack of oil (removed by the piston ring), and in combination with manufacturer's suggested (MIL) oil changes, which are 7,500 to 10,000, you'll have very shortened engine life expectancies (and we are already seeing that). In short, if you want your new Toyota engine to last 200K, you'll need to ignore the MIL and do 3K oil changes, and you'll still have premature wear.

Your only option is to disable the start/stop feature, burn a bit more gas, and keep the engine lubricated properly in the process.

100% on this ^^^. ASS should be opt in, not forced down our throats.

[NSXR]

Originally Posted by KevinC

I like this guy, but disagree with his assessment of wear on the engine with start/stop systems. I simply know too much about pistons, rings, and cylinder wear characteristics to make his kind of generalities. He's pretty good at pointing fingers though, I just wonder if he ever points them at himself. He sounds a bit butt-hurt TBH.

[KevinC]

https://www.roadandtrack.com/news/a6...nt-admin-says/

[tturedraider]

Originally Posted by DanG

I like that in my BMW it stays off once I set it off. I never have to worry about it. Next time I start the car it will still be off.

Amen!!! Two or three or four years after it was introduced on the F30 BMW made it so the on/off function remembered the last setting. Prior to that owners could ask the dealer to change the system to remember the last setting. Mine has been off since I bought my car. Of course, the very best way to disable it in a BMW is to always put the car into Sport mode, which disables it. So, in my car even if I didn’t have the last setting memory it would still always be off, because the first thing I do after starting my car is to put it in Sport mode every single time!!

[Efthreeoh]

Originally Posted by NSXR

The 300,000 km number also apparently appears in BMW's own carbon ceramic brake literature. I have it in pdf somewhere, it was for the F10, and BMW was basically saying that for a street driven car the CCB's would never need to be replaced, "never" meaning they would last longer than the service life (300,000km/186,000 miles) of the vehicle.



I think it's relatively easy to make a starter motor last to 200K, but not so easy with cylinder walls.

I honestly don't understand the fixation on the cylinder walls. Engine oils have additives that help the oil film stick to the metal cylinder walls. Once the engine fires, oil pressure builds and lubrication continues. You make it sound like the interference between the oil ring and cylinder wall is of high friction. If that were the case, engines would be drastically damaged and destroyed in a matter of days of just a few cold start events. The ASS is just refiring an already hot engine, which is near zero wear factor.

[NSXR]

Originally Posted by Efthreeoh

I honestly don't understand the fixation on the cylinder walls.

Rebuild enough engines and you'll understand why.

No sense in arguing about it, time will tell this story quite clearly.

[DFW_M]

Originally Posted by NSXR

This is incorrect.

The increased wear is on the cylinder walls because of a momentary lack of oil (removed by the piston ring), and in combination with manufacturer's suggested (MIL) oil changes, which are 7,500 to 10,000, you'll have very shortened engine life expectancies (and we are already seeing that). In short, if you want your new Toyota engine to last 200K, you'll need to ignore the MIL and do 3K oil changes, and you'll still have premature wear.

Your only option is to disable the start/stop feature, burn a bit more gas, and keep the engine lubricated properly in the process.

Where is the link to this proven data that you confidently share with us?

[DFW_M]

All of these "experts" that think their own "common sense" is meaningful should consider that none of the manufacturers would put a "feature" in any car that causes premature wear and requires a replacement in their cost. Auto S/S is not mandated in the USA and only chosen as the feature for EPA mileage improvements by the manufacturers. I do not believe that many BMW ICE buyers would care if posted MPG is worse by 2mpg without this feature

[c1pher]

Originally Posted by DFW_M

All of these "experts" that think their own "common sense" is meaningful should consider that none of the manufacturers would put a "feature" in any car that causes premature wear and requires a replacement in their cost. Auto S/S is not mandated in the USA and only chosen as the feature for EPA mileage improvements by the manufacturers. I do not believe that many BMW ICE buyers would care if posted MPG is worse by 2mpg without this feature

It depends if you end up paying the gas guzzler tax because you don’t have it. I think like mentioned above, allow the feature but make it so that you can just leave it off. I hate it too, not just because of the wear and tear but also in its implementation. In Porsches, you lose power steering and most other cars, the car just shuts off slightly prematurely before a stop, jerking the car and also doesn’t anticipate stop and go traffic very well when really it should not even be on due to safety in my opinion.

[DFW_M]

Originally Posted by c1pher

It depends if you end up paying the gas guzzler tax because you don’t have it. I think like mentioned above, allow the feature but make it so that you can just leave it off. I hate it too, not just because of the wear and tear but also in its implementation. In Porsches, you lose power steering and most other cars, the car just shuts off slightly prematurely before a stop, jerking the car and also doesn’t anticipate stop and go traffic very well when really it should not even be on due to safety in my opinion.

My 2023 G80 had this feature disabled once you clicked it off. I assume they changed this later. That is one button I push first after I start the car, however, it does not bother me any more than the screen display warning that sits there or the display of what seats have seatbelts on like I am driving a bus not a coupe... My 2021 M2C did not have the Automatic mirror folding feature and I had to push the button every time I parked...annoying but became the norm for me.

Some here suggest -- program the car to start in SPORT mode every time and tat solves the issue. I believe that may (I have no proof and do not want to sound as confident as some others in this thread) cause more unwanted premature wear than the S/S feature...

[RockCrusher]

Originally Posted by Efthreeoh

I'm pretty sure the 186,000 mile (300,000 km) milestone came from my initial reporting in 2013 of the E90 oil life monitor ceasing to calculate OCI after 300,000 km. I was the first E90 owner to discover the threshold existed through a diagnosis process at BMW of Sterling (Virginia). It's well documented here on E90 Post.

A decade ago, some car internet site took that thread and turned it into "BMW considers the life expectancy only to be 300,000 km." I assume based on a sarcastic remark I made in the thread on the subject. I went on that site and set the record straight.

The truth is I don't believe it and never have believed BMW thinks any of its models have a targeted lifespan of just 186,000 miles. My 35-year experience with BMW ownership has proven otherwise. I owned a 1989 E30 the reached 300,000 miles, I have a 1997 Z3 with 199,870 miles on it so far, and my 2006 E90 at 426,840 miles (as of yesterday). Further, if BMW actually set a life expectancy of just 186,000 miles, it would not keep parts in inventory for well over 20 years past the last build date of any of its models. As an example, my 27 year old Z3, which was a somewhat limited model sales volume wise, still has a majority of its parts available as new OE parts available from BMW.

Just wanted to set the record straight. The 186,000 mile life expectancy is internet myth.

I came across -- source long forgotten -- that a gasoline internal combustion engine has an expected lifetime of 10,000 hours of run time.

On average a non commercial passenger vehicle averages 30mph which over 10,000 hours of run time works out to 300,000 miles.

I drove my 2002 Boxster to 317K miles. Even at that mileage the engine was fine. It did develop a problem with its secondary air injection system which forced me to sell the car as a roller when I was told by a Porsche dealer -- who had already had the car a month and had failed to diagnose the root cause of the problem (but by prior agreement only charged me $125 diagnostics fee! -- I'd have to leave the car with a blank check which would cover possibly having to drop the engine perhaps even split the cases. That the car needed a clutch -- its original clutch! -- I declined to spend the money.

Oh, so the engine was fine even with 300K+ miles on it what *killed* it was the failure of some emissions systems.

[JABCAT]

Originally Posted by W2k

Auto start/stop has been around for long enough that there is very solid data on whether it causes premature wear and failure of starters and other components.

Short answer: No, it does not. It's an internet myth.

I don't think you can make a blanket "no it doesn't cause premature wear" statement. All AS/S systems are not equal, and this system in Jeeps was causing a lot of issues with the starters, secondary battery & primary battery.

First hand experience in a brand new '23 Grand Cherokee L Summit my wife ordered the auto stop/stop didn't work from the day we picked up the vehicle. Secondary battery replaced, still didn't work. Kept giving warning lights in the cluster. Only thing dealer could do was shut off warning lights & say "maybe they'll release a software update to fix that down the road".

We traded the Jeep (our 10th Jeep) 9 months after we purchased it due to constant software & systems issues.

You can find evidence of other issues related to auto stop/start across all brands.

[DrVenture]

Everything in life has pros/cons. Weighing all those pros/cons and putting it all into perspective is extremely tricky. Unintended consequences abound. Unknown variables abound.

Possibly the shortcut is to look at engine failures, starters failures, etc to see if there are increased failures that can be attributed to this function. Guys who repair/rebuild engines are not doing these types of analysis. Or any scientific analysis at all. Their sample sizes are minute.

It annoys me, so I tend to switch to sport individual. When it most annoys me is creeping into my garage trying to park precisely. When it doesn't annoy me is sitting in traffic or at a train crossing. But, it is not a mandate.

https://www.roadandtrack.com/news/a6...nt-admin-says/

"Car manufacturers are in no way required to include start/stop technology on their vehicles, and virtually every new car on sale today that has it allows you to turn it off. The one annoyance commonly voiced by folks is that many of those vehicles will force you to stab the “off” button on every key cycle because it defaults to on."

I would assume that just like variable light distribution in could be disabled in certain markets, or set to default to OFF via an update. All the EPA can really do is remove the incentive to include it in vehicles.

[Vindicator3]

Sad to see (in the Road and Track article) the EPA head trying to cast this in terms of climate denialism instead of just focusing on the tech, whether it works, and whether it causes other problems. I can't wait for his "fix."

In the same article, this seems to be the money quote for why I actually like it, having expected it to annoy me (given that my 540i is a mild hybrid):

"Vehicles with mild-hybrid electric assist will take that a step further and shut the engine off as you’re coasting to a stop, eliminating the rough sensation of an engine abruptly stopping. They’re typically much smoother on start-up, too, as the electric assist gets you moving off the line, giving the engine a chance to start after the car’s already started to roll forward. Many mild-hybrid-equipped vehicles will even shut the engine off while coasting, too, silently saving fuel in the background."

[NSXR]

Originally Posted by DFW_M

Where is the link to this proven data that you confidently share with us?

How about I answer that question with a question.

How many engines have you rebuilt?