Liqui moly 5139 diesel system treatment 250ml liqui moly 5139 p align left this diesel system treatment 250ml from liqui moly has been developed for diesel engine vehicles with common rail injection systems guarding the components of the fuel system against wear corrosion and deposits easy to use the fluid is simply added to the fuel when filling up in the process increasing the lubricating action including diesel fuels with low in sulphur low sulphur diesel according to din en 590