We’re using this to protect the gas tank, which is mounted under the chassis – i.e. in a space where it’s vulnerable to grit, dirt and road debris.
This is recommended by the suppliers of the gas tank, and claims to provide:
Heavy duty protection for underbody, wheel arches and other high impact areas. Powerful rust inhibitors based on the Waxoyl system displace moisture and seal the surface against further corrosion.
I think this is something where we’ll have to report back once we’ve had some time on the road.
£5 from Screwfix.