Two articles on general engine break-in:

http://www.stealth316.com/2-breakin.htm

http://www.geocities.com/MotorCity/7177/trdbreakin.html

The USDM EJ20 and EJ25 turbo engines are not a purpose-built, blueprinted race engines. They are passenger car engines designed for long life and durability. The main reason why most engine builders (and the Subaru factory) recommend not running the engine at sustained or high-load, high speeds is because the new engine cylinder walls and piston rings have to wear in to form a compatible oil retaining surface for lubrication and good ring seal. Until broken in, the heat generated by the two surfaces will be quite high. While full-throttle, high load runs may seat the rings more quickly, the cylinder walls and rings may not develop quite as good of a surface finish compared to the factory-recommended method. Ultimately, power produced is a result of a good cylinder to piston ring seal.

While my WRX is only one example, it uses no oil between recommended change intervals, I have gotten better than 28 miles per gallon when sticking to 65 mph on the highway using the cruise control, and I've turned 13.8 E.T.s at the drag strip with mild mods. I followed the break-in procedure in the Owner's Manual and presently have ~45k miles on the clock.

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0==WW==0
"…axles of evil…" - george w. bush

 

Why do people keep saying this crap? I never said that I know what my owner manual says but I would like to know what others did and how it affected their engines.

 

There are so many opinions on this topic. I could just as easily pull up two links that show breaking in an engine using the load-method works better than following the manual's recommended procedure.

As I said I broke my engine in aggressively, but not carelessly, and so far, with 2200 km I don't seem to burn any oil. My car runs very strong and doesn't seem to have any problems. So I guess I broke my engine in poorly then? It certainly doesn't seem like it.

Furthermore, from that first link you posted, the "expert" says that engine break-in should be done by the manual yet an article he sites, regarding synthetic oils during break-in, contradicts his "expert" opinion:

Secondly, this "expert" says to run the engine for 20 minutes at 2000RPMs yet the Bible...er manual, says not to maintain a constant speed. Hmmmm.

Let me pull up a commonly used site that is against following the user manual:

http://www.mototuneusa.com/break_in_secrets.htm

Also:

http://www.cessna.org/benefits/articles/breakin.html (first part of the article)

So I think the topic is fairly subjective. I'd hazard a guess that the automakers use a "conservative" break-in method that suits the driving needs, styles, and laws or their buyers. Most people don't know enough about their cars to begin with, let alone even read the manual, so trying to explain a relatively complicated break-in procedure to them would be pointless.

I'd wager that if you actually met an automotive engineer that designed the engine, they would tell you something quite different than what is written in the manual.

I say, as long as you don't abuse the car and are mindful and methodical with your break-in, you'll be perfectly fine.

 

when you think about what a break in is it almost would not matter how you run the engine because if you are lapping in the cylinder walls with the rings it shouldnt matter how fast or slow the motor is running

does anyone have a motor that burns lots of oil and has poor performance?

i think it has alot to do with the way the cylinder wall was lapped in the first place from factory

and dont think that the factory process is just for the cylinder walls it is also for the cams and crank and all other moving parts or the fact that the oil put in the car to break in is not motor but most likely closer to cutting oil which would make for a better reason to have the recommendations that the factory has

 

When should you do your first oil change?

 

I did my first at 152, then another one at 450, and again at 3600 (all highway from FL to CA through backroads etc. I switched to synthetic on my 3rd.

I just thought it was good to take all the metal out of hte oil that i could. Oils cheap, new engines arent.

 

what i am about to say has no scientific backing- nor is it endorsed by me, my employers or anyone affiliated with me.

here is a procedure that a friend of mine from japan has been doing for years. he has owned 3 subarus, 2 hondas, 2 audis and one bmw. when he bought his STi from me he drove his car to 4 grand in every gear and did it as much as possible until his odometer read 500 miles. from then he stated his car "is ready" for hard driving. i found it interesting the way he did his break in period. this post is open to scrutiny.



aloha from the summit of Mauna Kea

 

i have heard that before too

gental at first then beat it for a few hundred miles

 

Traditional car dealer advice is to treat it like a baby.

Most performance engine builders will tell you different.

Theres only so many miles, first few hundred, to get a really good ring seal.

Drive it tooo slow and you glaze the rings, IE you wear down the crosshatching without developing enough cylinder pressure to really push them outwards thus the seal isnt all that great. Beat on it way too hard and you wear them too fast, causing a poor ring seal.

Combine overall gentle driving with occasionaly taking it up through the gears (like a 2nd+3rd pull) is considered a good balance.

Real engine builders have crazy regimens like drive it for 10 miles at 2500 rpm ripping it up to 4000 once every 2 followed by crusiing at 3000rpm with rips up to 5000 and so on and so on.