Please find below an announcement regarding E10 fuel from Briggs & Stratton, with the same applying to other petrol engines.
Briggs & Stratton Petrol Engines - E10 Fuel
Briggs & Stratton overhead-valve and side-valve engines can both use up to, and including, 10% ethanol petrol.
Always use clean, fresh, unleaded petrol with an octane rating of at least 77 for side-valve engines or at least 85 for overhead-valve engines. We recommend the use of Briggs & Stratton Fuel Fit petrol stabiliser to keep fuel fresh for up to 3 years. When using E10-95 petrol, the dosage should be increased by 25%.
Buy fuel in quantities that can be used within 30 days. This will ensure that the fuel is always fresh and that the volatility of the fuel matches the season. Do not mix petrol with oil.
NOTE: We recommend NOT using petrol containing more than 10% ethanol (E10) blend and this MUST be removed from the engine before storage. Methanol-containing petrol must also NOT be used.
All Other Petrol Engines - E10 Fuel
The same applies as above, it is completely safe to use E10 fuel with the majority of your garden machinery, provided it isn't left in the machine for longer than 3-4 weeks maximum. Please refer to your user manual if you are unsure whether E10 is suitable for your machine. If it isn't, or you are unsure about using E10 fuel, you can continue to buy E5 fuel from forecourts by choosing super unleaded petrol, or you can purchase a long-life fuel called ASPEN (4-stroke petrol or 2-stroke pre-mixed petrol).