Diesel Fuel No. 2

Diesel fuel No. 2 (CAS 68476-34-6) is a refined petroleum middle-distillate — the same fuel-grade cut sold at the pump for diesel engines, spanning roughly C9 to C20 hydrocarbons. In fuel-system additives it is used as the solvent carrier: it dissolves gum, varnish, and carbon deposits and delivers the proprietary detergent active through the tank, lines, injectors, and combustion chamber. Compared with the light naphtha or xylene carriers common in this category, the diesel/kerosene distillate range has a higher flash point (typically above 60 °C) and lower vapor pressure, which keeps the concentrate's VOC content and inhalation exposure lower.

The distillate is EPA VOC-classified under 40 CFR 59 and is harmful to aquatic life with long-lasting effects if spilled. It is not readily biodegradable and is persistent in soil and sediment. Its dominant hazard driver is aspiration: the low viscosity of the hydrocarbon chain means it can be drawn into the lungs if swallowed, which is why products built on this carrier carry the H304 aspiration classification and a "do not induce vomiting" first-aid instruction.

The distillate also carries trace polycyclic aromatic hydrocarbons — chiefly naphthalene — from the raw feedstock. Even at low percentages, those trace aromatics are the regulatory ingredients that push the parent product onto the California Prop 65 warning list.