It seems Matthew is one end of the arguement and I would agree that 33 or 30 to one is not the issue. When you start thinking about 40:1 then it is an issue. An arguement on the Jawa club site is that 40:1 was introduced as a reaction to emissions laws but it is a significant risk to the survival of the crankshaft bearings. Personally I feel a ratio of 33:1 using a branded two stroke oil is a sensible compromise. It won’t break the bank any you can reasonably expect good lubrication of the engine bottom end.