Many thanks to those who posted advice on how to proceed, I know it wasnt my thread but I think we should both arrive at the same place.
If the OP needs any help from my travails just give me a shout.
What is the correct amount of SAE 30 oil to put in 5 litres of petrol for this engine?
The manual is not clear as it shows a l- pint as a measure for 1 gallon of petrol.