Hello to all,
I've been trough this for ages now, so you can rely on my advise if you want to!
When doing running in, you should always do at least 500 miles before going pedal to the metal! especially on cossies! My advise is, that after doing 500 miles running in, get into the pat and change the oil for fully synthetic. Do not race the car into high revs using mineral oil! Only after changing to fully/syn you can go as fast as you like. At this stage, you can raise the boost too! Do not run high boost during running in with mineral oil! Cossies are sooooo fragile
When building cosworths i use these type of oils:
Running in: Torco TR1 20w50(mineral oil)
After running in: Torco SR5 5w50 (fully synthetic)
My car is a 500+ bhp cossie and always used these types of oil and never had somekind of trouble regarding oil or oil pressures!
Hope i helped you out!