[sdhotwn]

I used to hand build engines (for Mazda's) and did tuning on the side to feed my racing habits. I'm also a mechanical engineer, have been racing for 10 years, and did engine research as part of lab work for a semester. I'm NOT an expert, but i have a solid background.

The RPM limit they recommend isn't bad, and the first 500-1000 miles it is reasonable to follow that. Varied load really is important. Relatively high throttle opening with some boost helps seat and wear the rings in, and can help reduce oil consumption, when doing that though, it's important to have some decent long decel periods immediately after. That helps wash the walls and pull vaccum to get the oil and metal shavings off.

The main reason for the recommendation as they give it in the manuals is if anything is tight, or people bounce it off the rev limiter (or fuel cut) you can get wear patterns or friction buildup that is less than ideal. Modern engines are so damn well toleranced now that catastrophic failure is essentially unheard of. The lighter loads DO help seat anything that may be slightly out of alignment and allows some of the assembly fluids to work their way out.

Also, many bearings and seals don't fully lubricate out and wear in until they've had some revolutions on them, and can heat up excessively with too many rpm's (hence the recommendation). Giving time for them to "loosen" and lubricate at temperature is another reason for the low rpm's for XXX miles recommendation.

I typically try to go out to the twisty roads for the first 200 miles in one session with lots of moderate cornering and up and down decel with limited rpm's and periodic large throttle opening. Higher pressures with low (but at operating) temperature seats the rings best with the least risk in my opinion. So that's what I do. I'm also absolutely adamant about an oil change at 1k. If you saw how much metallic glitter comes out during that oil change you'd think you damaged something.