How will the new Biofuel E10 upgrade affect older petrol outboard engines

A new biofuel will be introduced as standard at petrol stations throughout the UK this summer, and due to this we have been receiving a lot of questions regarding this from our customers. Below should answer these questions which have been copied from a Yachting Monthly article May 2021:

  • E10 petrol, which contains up to 10% renewable ethanol, will be introduced as standard at petrol forecourts in the UK later this year
  • E10 petrol, which contains up to 10% renewable ethanol, will replace the current standard of unleaded petrol known as E5, which contains 5% ethanol.
  • 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.
  • Boat owners are being advised to check their vessel’s manual or ask the manufacturer or dealer before filling up with E10.
  • E5 will continue to be available at many petrol stations for owners whose boats are not compatible with E10, although it is unlikely that marinas will install a second pump to accommodate the choice of either E5 or E10.
  • Owners with engines which are compatible with E10 petrol can mix the two grades of petrol when filling up.
  • Yachting Monthly expert Duncan Kent has said the increase in ethanol is a problem for sailors, as it attracts water.
  • Most petrol outboard fuel filters are only designed to remove debris, so water is still able reach the carburettor.
  • A water separating filter can also be fitted to the fuel system if practical, and old seals, pipes and fittings can be changed to ethanol-proof versions.
  • This can reduce the outboard’s performance and increase fuel consumption.
  • Bacteria and microbe growth caused by the water content can also cause filters to clog.
  • Kent recommends running the engine dry on simple outboards and non-injection engines.
  • If leaving the engine for longer than a couple of weeks, he recommends draining the entire fuel system down, including the tank.
  • Petrol should not be stored for longer than a month in a container, and it is best to buy fuel from an outlet with a high fuel turnover where possible.

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