Running-in oil

[Niall]

With regards to running in oil, its pretty conclusive that you just use mineral oil. I won't go through my running in because we all know i didn't torque a main bearing cap and destroyed my big ends but oil wise, i used a mineral oil for 200 miles then went onto semi synth for mapping and changed it right after mapping.
The running in procedure...Tbh i spent several evenings trawling the net and a few old books on this and there isn't really a conclusive answer. A lot of people seem to say its dependant on how you wish to use the engine. Like, if its a race engine, run it in fairly hard as that is how it will be treated for its life. Thats all well and good but we all know race engines won't last as long as a engine built for the road...but then thats a cost you accept when getting into track days or racing!
Personally, i went with the method Darren suggested. My car is road use and does get driven like my nan drives sometimes so i ran it in relatively hard, short sharp amounts of power and stuck below 3000rpm for the first 100 miles then gradually opened it up.