A diesel engine must be operated by a trained caretaker, and every engine has its own operating instructions. Before starting the engine, the levels of fuel, oil and cooling water (if not air cooled) should be checked, and topped up if any are low. During operation, the caretaker should check the fuel level and oil pressure, and that the pump and generator are functioning properly. Some moving parts may need to be lubricated manually. The engine speed should also be checked, because if it is too low, the engine will have a low efficiency and carbon rapidly builds up in it. This will increase the frequency with which the engine needs to be serviced. All data on fluid levels and running hours should be recorded in a logbook.
Every day, the outside of the engine must be cleaned and, in dusty conditions, the air filter must be checked and cleaned. In moderately dusty conditions, oil-bath air filters are cleaned once a week, dry-paper air filters a little less frequently. If the engine is connected to a pump or generator with a v-belt, the belt will need to be replaced regularly. Once a year, the engine house must be painted and repaired. The engine is serviced for preventive maintenance according to the number of hours it has run. <br>'''Every 50 hours''', the clutch (if present) must be greased. <br>'''Every 250 hours''', the filters must be cleaned or replaced, the oil changed, and the nuts, bolts and exhaust pipe checked. <br>
'''Every 1500 hours''', a major service overhaul will be needed, that includes decarbonising the engine, adjusting the valve clearance, etc. Diesel engines require a lot of simple maintenance and if this is done well, they can have a long service life. Therefore, the training and supervision of the caretaker are important. More complicated maintenance tasks and repairs have to be done by a well-trained mechanic with access to spare parts. The organizing committee must make sure that generator servicing is carried out on schedule, and that they can respond quickly in case the generator breaks down.