Complete fuel system cleaner Cetane booster & diesel treatment ULSD sulphur substitute lubricity additive Improved engine response and performance Compatible with all diesel fuels including ultra-low sulphur and biodiesels. Rislone Hy-per Diesel Complete Fuel System Treatment improves the quality of diesel fuel by increasing its cleaning ability, adding lubrication, removing contaminants, fighting corrosion, and helping to prevent the fuel from gelling & going bad. Simply put, it is the best all in one diesel fuel additive money can buy.