I've had to put 500 or so miles on a clutch before I could give it beans. This was 2 days before bug jam or action if I remember. I was up till 3am putting miles on it lol
It's nothing to do with the oil, that was just coincidence. There is nothing near the sump plug or oil filter to cause those symptoms. Have you scanned it for any faults as I'd say a sensor has thrown a wobbly
ASNU are a licences chain of injector cleaners it's a way of cleaning them. I have used them before as I have a centre near me that deals with landies. http://www.asnu.com/history.htm
There might be different castings on it. I went from a obd2 head to a obd1 head that had been played with and I had to cut a bit of the head away to get the rotrex charger back on