From the Stag Owners Club Forum
"The Advertisng Standards Authority (ASA) has investigated the claims made by Sussex Promotions t/a Fuel Diamond (Sussex Promotions) and published their ruling on 17 August 2022 (attached).
The report says "We told Sussex Promotions t/a Fuel Diamond not to make claims that the Fuel Diamond could prevent fuel/petrol from going stale or neutralise ethanol and therefore prevent damage to vehicles, or any similar claims, unless they held adequate substantiation to support them". This was on the basis that the following claims in their advertising were misleading and could not be substantiated: "PREVENT DAMAGE", "Neutralise the ethanol in petrol", "the product could stop or prevent fuel/petrol from going stale".
The manufacturer appears to have sidestepped the ASA ruling by signing-up one or more retailers, but personally I don't plan on buying the product anytime soon"
Other sources also say 'snake oil'
