If it's the same as this one
each 250ml bottle will treat 50 litres of fuel so 5ml per litre and will only do just over a Commer tank full (which holds about about 43 litres of petrol). The treatment should be added to the tank first so it mixes properly with the fuel. The 250ml bottle is less concentrated than the bigger 500ml bottles I linked previously which will do over ten fill ups. It won't matter if you put a bit too much in.
You can drive your van quite happily without the additive but It's an extra precaution against the effects of ethanol, don't let it stop you enjoying your camper.
each 250ml bottle will treat 50 litres of fuel so 5ml per litre and will only do just over a Commer tank full (which holds about about 43 litres of petrol). The treatment should be added to the tank first so it mixes properly with the fuel. The 250ml bottle is less concentrated than the bigger 500ml bottles I linked previously which will do over ten fill ups. It won't matter if you put a bit too much in.
You can drive your van quite happily without the additive but It's an extra precaution against the effects of ethanol, don't let it stop you enjoying your camper.