Cleaning your oil boiler or furnace is one of the most important things to do. Any oil boiler or furnace should be cleaned once a year. Not only does cleaning the boiler increase the efficiency and longevity of your heating system it also prevents other more serious events from occurring. When a technician cleans a boiler it involves; changing the nozzle, replacing the oil filter,cleaning out the sections of the boiler with a vacuum, and optimizing the burner to burn cleanly. Depending on the conditions observed other parts of the cleaning could involve cleaning out a power venter, replacing the pump filter, cleaning out a low water cutoff, or a number of other things. 

Furnaces require a couple additional checks when being serviced. Namely replacing the air filter and making sure the belt to the fan motor is crack free and is set correctly. Gas boilers can generally run for 2-3 years without having to be serviced if its not a conversion. An easy way to check if your gas boiler is in need of service is to look at the color of the flames. On most pilot boilers the flames will be easily visible, on some of the electronic spark ignition boilers they require you to open a viewing door. If the flame is an orange color at more than just the very tip of the flame, it's time to call your local technician. Clean your boiler regularly and you will increase the life of your heating system and squeak the most efficiency out of it during the heating season.