I suppose the only reason it that all of the anti freeze that is available in the UK is in concentrated form..........so it's supposed to be diluted to the correct strength with tap water. If you read on the back of the container that "this product can be used "neat" - no need to dilute" then maybe it would be ok.......also, in the Cossie owners handbook I think it does day to check.add anti-freeze to the correct strength