I decided to use POR-15 tank sealer

The main reason why ethanol is a problem for steel petrol tanks is because it absorbs water and then releases it into the tank. So water eventually pools in the bottom of the tank and corrodes it away. It's is different story for plastic and fibreglass tanks - I think it just dissolves those but I don't know for sure.

When it comes to guarding against the dreaded effects of ethanol, there are a few products around. I'm not sure there's a strong reason for choosing one rather than another but I decided to give POR-15 a go. The reason was because it cures with atmospheric humidity (water vapour). If ethanol is a problem because of the water it carries, it seemed to me that a coating that uses water to cure was a good match.

I bought a POR-15 kit some time ago. The instructions leave a lot to be desired in terms of the practicalities, I think. Also, it has been so cold out that I haven't had the will to use it. But Spring is nearly here so it's time to get cracking.

I found this step-by-step video from a company called Holden. It has a lot of sensible, practical advice, including the use of duct tape to seal up the apertures in the tank. I like the attitude of the venerable gentleman on the right - it has given me confidence to have a go. It is for a car tank but I don't think the differences are particularly problematic. At least not yet ... I'll post again when I've had a go myself.