I'll tell you how i did mine!
N75 Disconnected. 10w40 MINERAL engine oil.
Start from cold, run around the block a few times until coolant reached 90c, back to house and checked for leaks.
Then i set off out of town, avoiding idling, constant speeds, constant load as much as possible. Once on the more open roads, i started a series of controlled pulls in third gear, from ~1500rpm to 4000rpm, at 50% throttle, then lifting off and allowing the engine to coast back down (clutch still engaged). Over approx 10 miles i steadily increased this until i was doing 2000-6000rpm at 100% throttle, again lifting and letting the engine coast back down thru the RPM's, and driving for a few minutes steadily but avoiding constant load between pulls.
After a total of about 30miles i was back home.
Drained/refilled the oil and fitted new filter.
Then i drove the car normally, although i still tried to avoid constant load (ie motorway) for the first 500miles or so. When i did have to use the motorway i constantly varied my speed between 60 and 80 so the engine was seeing different loadings all the time.
I changed the oil again at 100miles, 250miles then 500miles, at which point the N75 went back on and i switched to 5w40 fully synthetic oil.
That first 25miles is crucial, you need load to get the rings bed in, and the overrun at high RPMs helps scavenge all the debris out the cylinders. Drive it like a granny during this period and the rings wont properly bed in, you'll end up with poor sealing, and a limp engine.
It worked for me, 5000miles later its still running and is very strong.
What i found odd was you could actually feel the engine getting stronger with each pull. First time i gave it some it felt totally flat, then as the miles wound on it got stronger and puller harder and harder with each pass.
