E10 or E5 fuel?

Should I be using E10 or E5 fuel?

We are still regularly asked this question and it is a valid one. Read on for our take on the E10 v. E5 debate. 

Unlike E5 petrol, which had previously been the norm and up to 5% renewable ethanol, the E10 grade contains up to 10% renewable ethanol. This makes it more environmentally friendly and reduces Co2 emissions, however some older engines may not be compatible with the new fuel, without modification, and there are other things to consider before filling up with E10.

All Honda outboards produced for the EU market since 1996 are compatible with E10.

All Tohatsu outboards are compatible with E10.

All Suzuki 4 strokes outboards are compatible with E10. 2 stroke models are NOT compatible with E10.

All Mercury/Mariner outboards built since 1996 are compatible with E10.

All Yamaha outboards built since 2003 are compatible with E10.

It is our recommendation that all owners check their owner’s manual in relation to care and storage guidance specific to their outboard.

So, what should I be using?

It is our recommendation to continue to use E5 fuel wherever possible.

If you are using E10 fuel, the entire fuel system should be completely emptied if the engine will not be used within a 3 week period. This is especially important in small, carburettor models. We are performing more clean out and replacement of carbs than ever before. Note; carburettor replacements due to fuel are not covered under manufacturer warranty.

E10 petrol has a higher ethanol content than E5. Ethanol attracts moisture and this can lead to performance & reliability issues.

The majority of outboard fuel filters are only designed to remove debris from the fuel and will not prevent moisture from reaching the carburettor or vapour separator and contaminating it with water. When water remains in the carburettor or vapour separator for any period of time, it can cause both starting issues and damage to carbs, fuel pumps & injectors.  This can start to happen in a very short period of time, so it is vital to remove E10 from your fuel system if your engine is not being regularly used. 

Can I Still Buy & Use E5 Petrol in My Outboard?

Yes! Although petrol pumps will now sell E10 as standard, Premium Unleaded will continue to be E5. So, although it may cost slightly more, it will still be readily available and in most cases, it will still be the preferrable option over using E10 for marine use. 

You can find the official, more general government guidance on E10 Fuel here:
https://www.gov.uk/guidance/e10-petrol-explained