The confusion was my fault Speedy. I was just wanting to know how many mls to add to a litre and using ":" as shorthand for "to". I realize now that you were talking the other way around, i.e. petrol to oil, 16 parts to 1 part, hence 16:1.
Max can correct me if I'm wrong, but I think he is suggesting 20:1 (fuel to oil ratio), or 1ml of oil to 20 mls fuel, which is a fair bit richer (fuel-wise) than what the manual specifies.
To avoid any further confusion, I'll just go with what Tyler suggested: 40 ml oil to 1 litre fuel, 160 ml oil to 4 litres fuel, or 200 ml oil to 5 litres fuel.
