Fuel filters for diesel service cannot be treated with the complacency given filters in gasoline service. Water should be removed at a point before the injectors. Some fuel filters combine water removal features and filtration features in the same package. Diesel fuel systems from process, to storage tanks, to engines, traditionally contain much more water than gasoline systems. Water is a definite problem in diesel fuels and it must be coped with.
Low temperatures tend to precipitate wax in diesel fuels.
In order to get the fuel to flow through filters correctly, it is generally heated in the fuel system of the engine. Certain lube oils are specifically designed for diesel service. The combustion process, blow- by products and engine loads are different in a diesel engine, as compared to a gasoline engine. The lube oil, therefore, must do a specific and different job, depending on whether it is used in diesel or gasoline service. The classification system covers various categories based on engine age, type and service.