Chainsaw Repair

FIRST OF ALL I LIVE IN THE UNITED KINGDOM
All petrol in the UK ranges from 95 to 101 RON
In general normal unleaded fuel has 10% ethanol in it.
the higher octane fuel may have ethanol in it but it depends where in the country you live.
I'm in Swansea. Wales and it seems as if i might be lucky in that the higher
octane fuel contains no ethanol. 
I have converted to high octane fuel in my machines this year. the octane rating is 99 RON.
I purchase it from my local supermarket where i also fill my car and have never had any problems.
As a safety precaution i use Ethanol shield additive in both 2 and 4 stroke engines. I use
Stihl HP Super 2 stroke oil which also has stabiliser in it

THE ONLY PROBLEM IS THAT HIGH OCTANE PETROL COST £1.40 PER LITRE (OUCH) AND RISING ALMOST EVERY DAY