is "break-in" really necessary

[poly_poly-man]

You are going to have to explain that statement.

All MFG info and info in this thread and other research I have seen on this subject says otherwise. Stay within the recommended range to allow all the hard parts to seat properly to provide better service later in the life of the motor.

if you let everything sit in, and you've been going 2000 rpm solidly the whole time, stuff won't necessarily be sat in correctly for higher rpm -> the first time you hit redline, bad stuff.

[mangostick]

So you never floor it or redline it during the first 1000 miles?

NO.. the moving parts need to seat first.. ripping to redline with a fresh engine= moving parts not seated correctly and not wearing properly.. this in turn = rebuild much sooner if not risk of early catastrophic failure.

That's not good for an engine. It needs to run through its entire rev range.

Not while its fresh. Not more than 1/3 to 1/2 its redline is perfectly fine for seating/bedding parts.

.. I think what you mean is that you dont want to keep a constant rpm during break in.. THAT is true, dont use cruise or keep same speeds for long periods while breaking the engine in as that practice can also cause parts to improperly seat and wear prematurely.

Some components seat and break in faster than others but for the most part the first 1k mi is a good well rounded number for a automobile application. Usually its a time frame of operating hours but no one has a hour meter in their car (though I think they all SHOULD have one).

You run a good chance of shortening an engines life by repeatedly running it hard without fully seating moving parts after assembly.

Performance engines are built with parts designed to take more abuse than a standard use engine. These take longer to fully break in because of their stronger material composition.

Bottom line, follow what the manufacturer recommends.. they dont make those statements for fun or to keep you from having fun, they do it to keep their warranty claims to a minimum.. aka.. getting engines to last as long as they should by properly breaking them in.

[Chader]

if you let everything sit in, and you've been going 2000 rpm solidly the whole time, stuff won't necessarily be sat in correctly for higher rpm -> the first time you hit redline, bad stuff.

I never suggested just rolling along at one, low RPM. Not sure why you assumed that

I questioned the statement about "flooring the throttle and running through the entire rev range". Both of which are specifically recommended NOT to do during break-in.

The accepted procedure is essential to keep below 4000 rpm and vary the rev range frequently. Avoid full throttle acceleration and prolonged periods at the same rpm.

I'm not going to waste my time listing more. If people actually care, they should read the manual.

[teflon_jones]

NO.. the moving parts need to seat first.. ripping to redline with a fresh engine= moving parts not seated correctly and not wearing properly.. this in turn = rebuild much sooner if not risk of early catastrophic failure.

Not while its fresh. Not more than 1/3 to 1/2 its redline is perfectly fine for seating/bedding parts.

Some components seat and break in faster than others but for the most part the first 1k mi is a good well rounded number for a automobile application. Usually its a time frame of operating hours but no one has a hour meter in their car (though I think they all SHOULD have one).

You run a good chance of shortening an engines life by repeatedly running it hard without fully seating moving parts after assembly.

Performance engines are built with parts designed to take more abuse than a standard use engine. These take longer to fully break in because of their stronger material composition.

I never said anything about repeatedly. I said that never running to redline in the first 1000 miles is a bad idea. A car needs to be run through its entire rev range so the parts get fully exercised in every manner possible. If you never run a car past 50% of redline for the first 1000 miles, you think that's a good idea?

.. I think what you mean is that you dont want to keep a constant rpm during break in.. THAT is true, dont use cruise or keep same speeds for long periods while breaking the engine in as that practice can also cause parts to improperly seat and wear prematurely.

That is not what I meant, but of course you're never supposed to use cruise for very long or run the same rpm for a long time. That's a basic premise that nobody can argue with.

[teflon_jones]

I never suggested just rolling along at one, low RPM. Not sure why you assumed that

I questioned the statement about "flooring the throttle and running through the entire rev range". Both of which are specifically recommended NOT to do during break-in.

The accepted procedure is essential to keep below 4000 rpm and vary the rev range frequently. Avoid full throttle acceleration and prolonged periods at the same rpm.

I'm not going to waste my time listing more. If people actually care, they should read the manual.

Please quote a section of any owner's manual where they state to NEVER go over 4k rpm.

[jd92677]

Please quote a section of any owner's manual where they state to NEVER go over 4k rpm.

New vehicle break-in driving
– the first 1,000 miles (1,600
km)
The performance and long life of your
vehicle are dependent on how you handle
and care for your vehicle while it is new.
Follow these instructions during the first
1,000 miles (1,600 km):
. Do not race the engine. And do not
allow engine speed to exceed 4,000 rpm
except in an emergency.
. Do not drive at one constant engine or
vehicle speed for a long time, either fast or
slow.
. Avoid starting suddenly and rapid
acceleration, except in an emergency.
. Avoid hard braking, except in an
emergency.
The same break-in procedures should be
applied to an overhauled engine, newly
mounted engine or when brake pads or
brake linings are replaced with new ones.

I would say that indicates never.

[mangostick]

I never said anything about repeatedly. I said that never running to redline in the first 1000 miles is a bad idea. A car needs to be run through its entire rev range so the parts get fully exercised in every manner possible. If you never run a car past 50% of redline for the first 1000 miles, you think that's a good idea?

Yes, I do. Its not a myth.. and its not hearsay. You break in the engine at lower speeds. End of story. Engines have to settle in.. not only from a fitment perspective but also thermally. If you think nothing moves/flexes inside that engine you're far from correct. The whole bit is wiggling around in there when pushed hard and even the block changes when thermally cycled. You romp on it before its properly settled in and you create stress fatigue that WILL Shorten its life.

There's a reason why people that build performance engines like to use a "seasoned" block for high hp use. Its a block with high mileage and hundreds of thousands of thermal cycles.. its settled and will not change. THAT is why you break in a new engine before stressing it. Its green... its never been cycled.. you have to let it go through the motions and "cure" so to speak before you can hammer on it. I've had various engines apart and its evident right away which ones were broken in correctly and which ones weren't.

I've a few personally built performance engines that have lasted well into "high mileage" age because they were broken in correctly. Those words in the manual aren't there for fun man.. they're there for a reason. Ignoring it can be an expensive mistake.

Most oem's do run the engines through a "initial" run in period.. but thats only for bearing bedding. It doesn't fully seat rings, thermal cycle.. none of the other important parts of a full break in. So yes, I DO think breakin at idle to half speed without constant speed operation is a good Idea.

You can do what you want with your car, its your rig. I'll follow the proper procedure because Its proven to me that it works.

[Chader]

New vehicle break-in driving
– the first 1,000 miles (1,600
km)
The performance and long life of your
vehicle are dependent on how you handle
and care for your vehicle while it is new.
Follow these instructions during the first
1,000 miles (1,600 km):
. Do not race the engine. And do not
allow engine speed to exceed 4,000 rpm
except in an emergency.
. Do not drive at one constant engine or
vehicle speed for a long time, either fast or
slow.
. Avoid starting suddenly and rapid
acceleration, except in an emergency.
. Avoid hard braking, except in an
emergency.
The same break-in procedures should be
applied to an overhauled engine, newly
mounted engine or when brake pads or
brake linings are replaced with new ones.

I would say that indicates never.

Quoted again for truth.

Thanks for taking the time to put that all down.

I have purchased several new cars and motorcycles and they all mimic that structure for break-in.

[mycologist]

It doesn't say anything like "never".

What it does indicate is that they will still warrant the engine even if it has been "raced" during the break-in ostensibly due to an emergency situation (something they could never expect you to prove). I.e. it is a good idea to limit this activity but you should be fine if you break the rules occasionally. Otherwise it would be cost prohibitive to them to warrant the engine without providing it fully broken in.

I would suggest that there is no good publicly available data to warrant continuing this argument, but carry on if you please.

[anxiouz]

When I pick up my car I plan on trying to take side-streets as much as possibly to force me to vary my speeds more. And I'm going to stay below 4k rpm for 600-700 miles. But then I'm going to get on it once every 100 miles or so until I'm past 1k miles. Not full gear pulls to redline, but full load and seeing some boost.

I believe in allowing the engine component to gradually seat themselves but am not so set on the 1k milestone. Like everything a manufacturer suggests, I believe it to be a conservative rule. If you can break-in the car for 2k miles that's likely even better but who wants to wait that long lol.

I also believe that the "break it in like you'll drive it later" has merit. But I think you need to gradually get to that point....drive it gingerly and then little by little go to higher rpms and load.

[Chader]

It doesn't say anything like "never".

You really want to split that hair

Sure it doesn't say NEVER. But it does use the phrase "except in an emergency".

I take that statement to mean, do this only if you need to avoid an accident or other dangerous situation.

It doesn't mean you should ring the car out whenever you feel like it and can't show enough will power to follow a recommended procedure. Will it hurt the car? Maybe, maybe not.

Do what you want, but I choose to listen to the professionals that actually build the car rather than supposed experts.

[mycologist]

You really want to split that hair

Sure it doesn't say NEVER. But it does use the phrase "except in an emergency".

I take that statement to mean, do this only if you need to avoid an accident or other dangerous situation.

It doesn't mean you should ring the car out whenever you feel like it and can't show enough will power to follow a recommended procedure. Will it hurt the car? Maybe, maybe not.

Do what you want, but I choose to listen to the professionals that actually build the car rather than supposed experts.

You may call it splitting a hair, but to the manufacturer it is a question that is important in the multi-million $ range. Yes, they do split that hair on purpose IMO. Their statement is not what you said. And they don't decide to state that on the basis of "maybe" more like "highly unlikely to unheard of".

Where are the forums reports of all these blown up cars from improper break in? They don't exist even though many people ignore the recommendation (something I followed BTW).

[Chader]

Their statement is not what you said. And they don't decide to state that on the basis of "maybe" more like "highly unlikely to unheard of".

Out of curiosity, what does it mean then? I suspect it is almost for safety liability reasons. Something like, if someone tries to follow the procedure, stays under 4k when they should actually nail it to avoid an accident if someone runs a red light. Suby doesn't want a suit if a person gets hurt by following the procedure rather than taking the necessary actions to exit a dangerous situation.

Where are the forums reports of all these blown up cars from improper break in? They don't exist even though many people ignore the recommendation (something I followed BTW).

I never made any claim of blown motors. In fact, I doubt there are many instances of blown motors unless someone does something really bad like missing a shift that results in a large over rev or some similar issue.

Personally, I feel the issue of improper break-in shows itself further down the line (like years and many thousands of miles) in the form of poor performance, oil consumption, etc.

[mycologist]

Out of curiosity, what does it mean then? I suspect it is almost for safety liability reasons. Something like, if someone tries to follow the procedure, stays under 4k when they should actually nail it to avoid an accident if someone runs a red light. Suby doesn't want a suit if a person gets hurt by following the procedure rather than taking the necessary actions to exit a dangerous situation.


I never made any claim of blown motors. In fact, I doubt there are many instances of blown motors unless someone does something really bad like missing a shift that results in a large over rev or some similar issue.

Personally, I feel the issue of improper break-in shows itself further down the line (like years and many thousands of miles) in the form of poor performance, oil consumption, etc.

In my mind it means when they crunch the numbers they can statistically afford to warrant the motor to 60k miles no matter how poorly it was broken in. Otherwise they would give it to you broken in or not offer the warranty.

What kills WRX motors long term (assuming we are excluding the defective ones)? It seems like most of the headgasket headaches from the late 90's 2.5l have been eliminated. Spun bearings from low oil pressure are number one in my mind. Cracked rings and eroded pistons from improper tunes running way lean and in det. would probably be up there. Failure to change the timing belt or it failing prematurely, etc.

None of these things seem break in related, and without them most will hit a ton of miles.

[jd92677]

This is such a silly arguement but I'll keep it going. Just 2 points to make. 1) I think it's pretty safe to say that Subaru has built more engines than everyone on this forum combined, so why would you not do what they feel is important enough to add it to the owner's manual? and 2) Would you buy a used WRX from someone that did't feel Subaru's recomended break in procedure was important? It's your car in the end and you can do what you please but I know how I would answer those 2 questions.