I have done a search on the forum for details about the differences in 2 stroke oil and I understand that "you get what you pay for" and that fully synthetic is better than semi. But what I arent sure of is whether I should follow the Beta instructions for my 2006 250 Rev 3 and use 70ml of semi synthetic oil in 5 litres of petrol, or whether I should take on board peoples advice on the forum from other threads and use fully synthetic as it is supposed to be better stuff???

Bet you a fiver you wont notice the difference. Havnt a clue whether mine is full or semi, but it smells of strawberries and thats a beautiful thing.

This topic has been done to death over the years, let's not start it again. If in doubt mix semi and full 50/50 and make do with semi-fully synthetic fully-semi synthetic.

This topic is also beat to death on a Chainsaw forum that I watch. People spend far too much time worrying about which exceptional product to use. Don't go cheap and start using oil made for boat motors or snowmobiles - use a good quality synthetic or synthetic blend made for motorcycles and you will never notice the difference. Most of the problems occur when you either use old fuel or something gets in the carb jets and make the bike run lean.

If the bike is not running right find out why - don't just keep riding and hope that it will cure itself.