official word on "break in"
After reading many discussions and seeing much disagreement, here is the official word from the manual, typed out word for word:
Moving parts need breaking-in time to adjust to each other. Please follow the instructions below in order to achieve the optimal service life and economy of operation for your vehicle.
Engine and differential
Always obey all official speed limits.
Up to 1,200 miles/2,000 km
Drive at varying engine and road speeds, but do not exceed an engine speed of 5,500 rpm or a road speed of 105 mph/170 km/h.
Do not depress the accelerator all the way.
From 1,200 miles/2,000 km to 3,000 miles/5,000 km
Engine and road speeds can be increased gradually up to a traveling speed of 135 mph/220 km/h. Use the maximum speed only for brief intervals, e.g. when passing.
The transmission begins functioning at an optimal level only after a distance of approx. 300 miles/500 km. Do not exceed engine speeds of 5,500 rpm during this period.
Due to technical factors associated with their manufacture, tires do not achieve their full traction potential until after an initial break-in period. Therefore, drive cautiously during the first 200 miles/300 km.
Brakes require an initial break-in period of approx 300 miles/500 km to achieve optimized contact and wear patterns between brake pads and rotors. Drive cautiously during this break-in period.
The function of the clutch reaches its optimal level only after a distance driven of approx. 300 miles/500 km. During this break-in period, engage the clutch gently.
Following part replacement
The same break-in procedures should be observed if any of the components mentioned above have to be renewed in the course of the vehicle's operating life.
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I like what what already posted by GT3 Tim (I think that was his handle, but anyway), he said...
Many things can happen. One guy I knew hammered on his new car and proceeded to break some piston rings. Result, massive oil consumption and a new motor to fix it!
You can break or chip/damage the piston rings. Thus, scoring the cylinder walls...ouch! New motor time!
You can damage the valves and valve seats.
You can spin a bearing...
You can do all sorts of nasty crap to it!
You could also damage the tranny, but this is less likely.
New motors are build to some fairly tight tolerances. Typically, the higher performance the car, the tighter the tolerances. Thus, things need to "seat" and wear-in. By taking it easy on the car, and altering rpms (no long cruises at 65mph!), everything will seat nicely. Then you can hammer on it.
As for symptoms...your original question...the guy I spoke of had massive il consumption. If the problem were in the valve seat, you prolly wouldn't notice anything until down the road, when you end up burning a valve. Other than that, I dunno. Just take it easy on the car for a while. All sorts of stuff is breaking in...and there WILL be tiny metal shavings as a result.
I highly recommend changed in the oil at about 500 miles too. I would also recommend changing the gear oil, etc. at that time. Reason being, that this is the worst time for wear. Every rotaing or reciprocating part is going to be shaving off a little material. Best to flush it out ASAP. That's how I see it and thats what I will be doing. I have done it with every car I have owned in the last 20 years or so...you would be amazed at how much metal you will find on the magnetic drain plug...after you see that, you will be glad you changed all the fluids!
To each his own though...I am a bit more "careful" with the fluids than others. But to me, it is a small investment for some peace of mind