Combustion engine and method for extending the useful life of the fuel

The invention relates to a combustion engine (1), preferably a piston engine, in particular a motor vehicle or a working machine with a fuel tank (5) for fuel, in particular bio-diesel and / or fuel with a proportion of biodiesel, for operating an internal combustion engine (2). The invention is characterized in that means for minimizing the fuel temperature (6) are provided. Further, the invention relates to a method for extending the useful life of fuels in a combustion engine (1).