[pengpeng28]

hi all, picking up my new m2 soon and wondering if the run in period is a myth or absolutely necessary and how people approached. Just drive under 4k RPMs for 2k kms?

[aerobod]

Originally Posted by pengpeng28

hi all, picking up my new m2 soon and wondering if the run in period is a myth or absolutely necessary and how people approached. Just drive under 4k RPMs for 2k kms?

From the owners manual:

[mike@x-ph.com]

The common thinking is not to run the car hard for the first 1000 miles, but if BMW were serious about it, they would have limited your RPM to 5K during that time.

The fact that they allow you to run the car as you wish tells me this is merely a suggestion and not an absolute requirement.

[Info@mad-us.com]

I always very my rpms through the range and keep it at a relatively low load to seat the rings for a couple hundred miles. After that it's not really the engine but the other components you are being easy on to wear in properly

[Bumpinjeep]

Vary the RPM, use engine braking when slowing down, don't use cruise control, and don't slam the gas and redline it. Not really difficult to do. You should be able to get it done in a month or so and you're going to have a missle afterwards. No need to rush it and potentially break something.

[dissident111]

I did mine in a week and a half. I just made some routes to drive daily once or twice and put about 100 miles a day. Now I only drive like 5 miles a day lol.

[Info@mad-us.com]

Originally Posted by dissident111

I did mine in a week and a half. I just made some routes to drive daily once or twice and put about 100 miles a day. Now I only drive like 5 miles a day lol.

Think about all the built engines that get a very short break in period then go right on the dyno. It all happens faster than most people think.

[aerobod]

Originally Posted by Info@mad-us.com

Think about all the built engines that get a very short break in period then go right on the dyno. It all happens faster than most people think.

A built engine will have somewhat different spec than a stock engine that is designed to take higher stress, though. For example the 2 litre 260bhp naturally aspirated engine I built recently had twice the ring gap of stock and 50% higher big-end and main bearing clearances running a 10w40 break-in oil switched to 5w50 synthetic at 500km, instead of the typical 5w30. Core break-in was 20 minutes at 3000RPM for rings and tappets, followed by 1/3 to 2/3 load and revs which were varied as much as possible for 500km, then a day's worth of full dyno pulls before track use.

With a similar regime on a stock engine with stock ring gaps, the initial break-in friction could cause a ring expansion that would fully close the gap if the engine was run too hard too soon, that could lead to ring bind and a broken ring.

Built engines are not really aimed at the longevity or oil consumption goals of a stock engine, so with higher clearances they can be run harder and sooner than a stock engine.

[Info@mad-us.com]

Originally Posted by aerobod

A built engine will have somewhat different spec than a stock engine that is designed to take higher stress, though. For example the 2 litre 260bhp naturally aspirated engine I built recently had twice the ring gap of stock and 50% higher big-end and main bearing clearances running a 10w40 break-in oil switched to 5w50 synthetic at 500km, instead of the typical 5w30. Core break-in was 20 minutes at 3000RPM for rings and tappets, followed by 1/3 to 2/3 load and revs which were varied as much as possible for 500km, then a day's worth of full dyno pulls before track use.

With a similar regime on a stock engine with stock ring gaps, the initial break-in friction could cause a ring expansion that would fully close the gap if the engine was run too hard too soon, that could lead to ring bind and a broken ring.

Built engines are not really aimed at the longevity or oil consumption goals of a stock engine, so with higher clearances they can be run harder and sooner than a stock engine.

Good points for race engine specs. Personally i've always driven all of my bmws pretty hard after 300 miles or so and always performed a leak down around 30k miles and it's always been perfect. I've always been more worried about clutch and pad break ins.

[yoon_209]

Originally Posted by mike@x-ph.com

The common thinking is not to run the car hard for the first 1000 miles, but if BMW were serious about it, they would have limited your RPM to 5K during that time.

The fact that they allow you to run the car as you wish tells me this is merely a suggestion and not an absolute requirement.

BMW can void your warranty if you exceed the recommended RPM limits during the break in period. BMW techs are the record stating that.

The cars come with special oil and diff fluid that is changed out with regular at the break in service.

[c1pher]

Originally Posted by mike@x-ph.com

The common thinking is not to run the car hard for the first 1000 miles, but if BMW were serious about it, they would have limited your RPM to 5K during that time.

The fact that they allow you to run the car as you wish tells me this is merely a suggestion and not an absolute requirement.

Sure it could also be a way to deny warranty claims if things go wrong when you didn’t follow the instructions.

[ednir98]

FortNine made a great video on engine break-ins. I know bike engines are different but there are some similarities to a car. Non-bike specific stuff starts around the 1:40 mark

Big point he made in this video was to not just pull a 1200 mile road trip on the highway to satisfy the break in period. Variance in road type, RPM and driving style seem to play the biggest roles in seating your piston rings properly.

[RockCrusher]

Originally Posted by mike@x-ph.com

The common thinking is not to run the car hard for the first 1000 miles, but if BMW were serious about it, they would have limited your RPM to 5K during that time.

The fact that they allow you to run the car as you wish tells me this is merely a suggestion and not an absolute requirement.

The reason behind the factory not limiting the engine's performance during break in is liability concerns.

[RockCrusher]

Originally Posted by Info@mad-us.com

Think about all the built engines that get a very short break in period then go right on the dyno. It all happens faster than most people think.

Built engines are different and any real comparison between a built engine and a mass produced engine intended for a passenger vehicle is apples to oranges.

What break in happens on the dyno is the rings seat. (By observation of a newly rebuilt engine in a car the rings seat in just a minute or two of run time.)

This initial break in -- at the factory -- may not even involve the engine actually running on its own power. The engine can be placed in a fixture which has an electric motor spinning the engine and compressed air being fed to the engine to cause the rings to press against the cylinder walls enough pressure to seat the rings.

Even if the engine on the dyno runs under its own power the time the engine spends on the dyno does not represent real world usage -- mainly varying load over time combined with staying below some RPM threshold -- that the engine should receive to complete the entire break in process.

Also whether the engine runs on its own power or is driven by an electric motor the time on the dyno/fixture provides the factory the ability to check engine sensors/telemetry for any signs of issues.

The M2 break in mileage is 1200 miles. At an average speed of 30mph that's 40 hours of engine run time. Ain't going to do that on a dyno.

And an engine on the dyno doesn't provide the drive train time to experience break in. Even the tires require several hundred miles of usage to shed their out of the mold squirely road feel.

[M_Power Rob]

Originally Posted by RockCrusher

Built engines are different and any real comparison between a built engine and a mass produced engine intended for a passenger vehicle is apples to oranges.

What break in happens on the dyno is the rings seat. (By observation of a newly rebuilt engine in a car the rings seat in just a minute or two of run time.)

This initial break in -- at the factory -- may not even involve the engine actually running on its own power. The engine can be placed in a fixture which has an electric motor spinning the engine and compressed air being fed to the engine to cause the rings to press against the cylinder walls enough pressure to seat the rings.

Even if the engine on the dyno runs under its own power the time the engine spends on the dyno does not represent real world usage -- mainly varying load over time combined with staying below some RPM threshold -- that the engine should receive to complete the entire break in process.

Also whether the engine runs on its own power or is driven by an electric motor the time on the dyno/fixture provides the factory the ability to check engine sensors/telemetry for any signs of issues.

The M2 break in mileage is 1200 miles. At an average speed of 30mph that's 40 hours of engine run time. Ain't going to do that on a dyno.

And an engine on the dyno doesn't provide the drive train time to experience break in. Even the tires require several hundred miles of usage to shed their out of the mold squirely road feel.

You really need to post in reality (or your own words/knowledge), not regurgitating what is written in a book, internet, etc.

You have heard of a race break in? For normal driving, that motor is truly broken in at 500 miles. We all do 1200 miles cause that is what BMW tells us to do.

[M_Power Rob]

Originally Posted by yoon_209

BMW can void your warranty if you exceed the recommended RPM limits during the break in period. BMW techs are the record stating that.

The cars come with special oil and diff fluid that is changed out with regular at the break in service.

The dealership, and especially a tech, cannot void a warranty. People love to abuse that statemet.

What special oil/fluids...please, do tell.

[NewToM]

Originally Posted by M_Power Rob

The dealership, and especially a tech, cannot void a warranty. People love to abuse that statemet.

What special oil/fluids...please, do tell.

For the price we pay for the car I am assuming unicorn blood?

[Carefree]

Originally Posted by yoon_209

BMW can void your warranty if you exceed the recommended RPM limits during the break in period. BMW techs are the record stating that.

The cars come with special oil and diff fluid that is changed out with regular at the break in service.

💩

[mike@x-ph.com]

Originally Posted by RockCrusher

The reason behind the factory not limiting the engine's performance during break in is liability concerns.

it limits performance when you are running low on fuel.

[yoon_209]

Originally Posted by Carefree

💩

I didn’t believe either and thought it was BS until I watched this video. This is all taken at the dealer. Watch the whole thing and decide for yourself.

[yoon_209]

Originally Posted by NewToM

For the price we pay for the car I am assuming unicorn blood?

Watch the video I posted and decide for yourself

[yoon_209]

Originally Posted by M_Power Rob

The dealership, and especially a tech, cannot void a warranty. People love to abuse that statemet.

What special oil/fluids...please, do tell.

Watch the video.

The tech says the oil is like a mineral oil that is light and thin and meant to clean the engine from contaminants or shavings

I stand corrected, if you exceed the mileage for the break in they can void your warranty not necessarily RPM limit

Also they go into the computer via ista to disable break in mode and other things