Biofuel upgrade may affect older petrol engines

From the 1st September 2021, Petrol is changing to reduce overall carbon dioxide (CO2) emissions. MDL has been supplying E5 Petrol, which has up to 5% renewable ethanol, but this has now changed to E10 with up to 10% renewable ethanol. This is an automatic change over and supplies of Standard E5 Unleaded will no longer be available.

Although the Government has said that E10 is compatible with 95% of petrol-powered road vehicles, it has acknowledged that some older petrol boat engines may not be compatible with the new fuel.

Ethanol is hydroscopic and can absorb water from air and condensation. The long-term storage of E10 petrol, as is often the case with boats over the winter period, could cause a water build up in the fuel tank and engine parts. In older engines the water may cause rust and corrosion on some metals. Water in petrol can also be very damaging to the engine.

Most petrol outboard fuel filters are only designed to remove debris, so water can reach the carburettor. This can reduce the outboard’s performance and increase fuel consumption.

Ethanol is also corrosive to some plastics, glass fibre and rubber seals and fixings, causing leaks in older engines.

Boat owners are being advised to check their vessel’s manual or ask the manufacturer or dealer before filling up with E10.