Sorry Ess_Three, I was commenting on the 'general populace' who tend to rely on their point-of-sale or bloke next door as a guide to how to treat a new engine. I generally agree with your views. You obviously know what you are talking about, as do I.
I had a Mk2 GTI which I ran for close to 100,000 miles from new without using oil. Oil changes were done at 10,000 mile intervals and only fully synthetic oil was used. It was always driven sympathetically when cold and allowed to warm up before being used to the full.
That car was treated to a reasonably careful running-in period of around 1000 miles. As you say, no labouring the engine and no high revs. I didn't adhere to any strict guide, although I did (mostly) keep the engine below 3500 rpm for the first few hundred miles. After passing it to my brother the engine was torn down as a precaution and presented us with what basically amounted to a brand new set of components (much like your ABF) - I was astonished. As much as German engineering, I put this down to using the right oil, treating the engine well and yes, care running it in when new.
A bench-run high performance engine from the likes of Porsche or Ferrari will obviously not necessarily require a careful running-in procedure and modern tolerances are often held more tighly than 20 years ago. However, be under no illusion that all mass produced engine tolerances are so narrow or specified in such a way as to make them ideal. A cam lobe ground on machine A will still need to wear slightly in order to conform to a follower similarly finished on machine B. Asperity contact will still occur under high loads and boundary lubrication conditions. Lubricants will still carry contaminants around the engine.
I will concede that for many modern engines which you are going to keep for 5 years/50,000 miles you probably don't need to worry about being careful with running it in. How you treat it day-to day (allowing oil to warm up, not labouring the engine at low speed etc) and regular oil changes with decent synthetic oil is far more important. I would mention however that turbochargers turn very, very quickly and have bearings which are far more sensitive to wear particulate, oil degradation and other contaminants. Personally, I would want to carefully run in any turbocharged car (and even perform an early initial oil change) to ensure longevity of the turbo if nothing else.
Following the general guidelines given by T_T or the more basic good-sense advice from yourself to treat the engine carefully when new can avoid unanticipated damage which might well result in accelerated wear or even premature failure. You never know when you might want to keep a car for 12 years - I know I didn't.
