Fluids and filters in Cummins engines ensure proper lubrication, cooling, and contaminant control. Engine oil reduces friction and carries away heat. Coolant regulates engine temperature and prevents corrosion. Fuel filters remove particulates to protect injectors. Oil filters trap debris to maintain lubrication quality. Air filters prevent dust and dirt from entering the intake. Transmission and hydraulic fluids support smooth mechanical operation. Cummins specifies fluid types and filter intervals for optimal engine life.