Diesel oils (gas). Diesel oils are next to kerosene, distilling at 350-400 ° C, light oil character. These are unrefined products. Diesel oils used in Poland today are divided into three groups: I / L diesel oils for high-speed injection engines - summer, diesel oils type II / L for low-speed injection engines - summer, I / Z diesel fuel for injection engines of both types mentioned above - winter. Diesel engine oils are also obtained from coal distillation products, but they are not as good as petroleum oils (purulent), because they have low cetane numbers. They can only be used for large ones, slow running engines. Diesel oils are assessed in terms of the following properties: freezing point, viscosity (viscose), cetane number, calorific value, impurities and water content, sulfur content. According to viscose, oils for various types of diesel engines are classified. Diesel fuel must be clean, free of suspensions and transparent. The cetane number is an indicator of the suitability of diesel fuels as fuels for diesel engines, depending on the nature of the raw material, which fuel comes from. I / L diesel fuel is used for high speed injection diesel engines, with the number of revolutions above 800 to min. during the summer. Type II / L is a fuel for low speed injection engines with a speed of less than 800 to min. and for solid industrial diesel engines in the summer period. The I / Z type is used similarly to the previous types, but during the winter. This fuel can be used for RPM injection engines 800 per mm. In construction, diesel fuels are used for: 1) motor vehicles such, how: trucks with diesel engines (average wear rate 34,68 1 on 100 km mileage) , diesel buses (average wear rate 23,63 1 on 100 km mileage), special cars with a diesel engine (average wear rate 14,31 1 on 100 km mileage), diesel tractors (Diesel) . 2) construction equipment, like for example. for excavators, bulldozer, road rollers, graders, diesel locomotive, scrapers, crane's, compressors and for smaller equipment.