Perhaps if you aren't changing your oil. I have changed my oil, regularly. As far as the metals shavings go I can see how the build-up in the oil could cause long-term damage. But running the engine hard, coupled with an oil change at the proper intervals, and the appropriate oil - might resolve that issue.

I read that some techs think its better to run the engine hard - I wish I could remember which issue - this was in Motor Trend.

One of the editorials discussed the "Myth" of break-in periods and discussed both sides of the story: driving conservatively for the same reasons you provided and also driving hard - which some experts argued mroe efficiently "bored out" the engine if you will - for lack of a better term. I am not well-versed technically though their argument seemed to make sense.

I'm going to try and dig this article up.



In fact, 2 of my friends have g35's and having been in, and driven my car, they told me that mine feels a little faster than theirs.

Could be for any number of reasons though I am only 12K into my car, I have a few friends who wrung their cars out from day one...and 30k miles later their cars still run strong and im talking about a 04 TL, 04 Maxima, and 04 WRX.

 

This subject is forever in debate. I consider myself an accomplished mechanic, having done it professionally and on professional race teams, in shops and in my own business. Even in the presence of other, experienced and knowledgeable people, this conversation never really ends in agreement.

The mfgr wants you to break in the engine softly, mainly to make sure you don't take the opposite course and blow the thing up in the first week of ownership. Imagine if the manual said "go for it big guy...".

The main consideration I focus on when breaking in a new engine/tranny is to establish the wear patterns in bearing races, cylinder walls, cam lobes, etc. the way they will be expected to run under the conditions/purpose of that engine. Setting the rings is a function of establishing their fit in the cylinder and how they will "ride" on the cylinder wall. Some people invision the rings actually etching themselves into the wall. Not the case. No matter the precision by which they are made, all parts will need to polish themselves against each other to eliminate the near microscopic imperfections that exist between the two. Running the engine at low speeds will do this, but it will take longer and may not "set" the various parts at their full potential of contact (with a micro thin film of oil between them, of course). High revs, resulting high combustion pressures caused by an open throttle will force outward pressure on the rings and cause them to polish and perfect their fit not only faster, but under the type of loads that they could encounter at a later time, post break in. If they are not fully "perfected" at break in, then what do you think happens when you apply higher pressures later on? They are subject to further seating. This is true throughout the engine. Bearing races, gear faces, etc, all establish patterns and polish. You decide what that will be and how long these items "float" before they seat themselves.

Varying the revs and driving conditions is really a function of applying pressure across the spectrum of movement within the various parts range of contact. When accelerating, combustion pressure is felt throughout and pushes on everything. Close the throttle and a vacuum is created, reversing that pressure and creating opposite wear forces. It also creates a vacuum in the combustion chamber and helps to suck oil past the rings to lubricate the cylinder walls. Higher revving, harder accel/decel multiply the above exponentially. Higher oil pressures don't hurt either.

Most of my friends and acquaintences that build, race, maintain, etc would agree that creating the above scenarios, keeping in mind the way the car will ultimately be expected to perform is the way to go. But some others would disagree, as will here also.

The right thing to do? Following the manual will not steer you wrong and it's a safe approach.

 

Very good explanation. That actually makes sense - thanks.

 

I took it easy for the first 500 miles keeping it under 5000 rpm. Then up to 6000 rpm until 750 miles. After that I started driving the hell out of it. Judging by the few street encounters I've had, I'd say my car is running great.

 

here i had the exact same question....read this

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

 

That's been bouncing around the internet for ages. Well, maybe right after Al Gore invented the internet! LOL

Let it warm up well before any hard driving. And warm it up driving, not sitting in the garage more than a minute. Then driving it normally. That means building more revs as the miles pile on. Just quick sprints letting it coast down.
Never holding it at one speed when cruising. Don't use your cruise control, just shift between 4th and 5th every few minutes on long trips.

New tires should be broken in for a few hundred miles. Avoiding high speed running and hard cornerning until they take a set. Same goes for new brakes.
But a few hard braking sessions (just short of lockup) early on when driving on an open road (like 60 to 15 mph) then letting it cool for a while.. repeat about 10 times. That should avoid getting any glaze or deposits on the rotors and help the pads take a seat for better braking.

Some swear by the fast break-in when new. Maybe there is something to it, and maybe it shortens the life on the long end. I don't know. Just thought I would throw in some common sense methods that always worked for me.

 

Good stuff.