The oil filter is a consumable cartridge type which should be replaced either at intervals advisable in the manufacturer's service schedule. From the pump, the oil flows through this special channel, and on getting to the filter, it gets to the engine lubrication points. If the filter is clogged such that the oil flow is impeded a relief valve will pop open and bypass the filter canister so that oil pressure continues feeding the engine, but this is with unfiltered oil. To replace the filter element, you need to put a receptacle under the filter so as to collect dripped oil, then remove the middle bolt and pull the canister. Take out and dispose the filter element, and take out also the rubber sealing ring from the mounting place. Wash out the interior of the canister for any deposits such as dirt or sludge and replace the filter element. Replace a new sealing ring on the mounting such a way that it fits into the groove without rotation. Re-construct the canister to fit properly on the seal then tighten the fixing bolt. When tightening retighten with a momentary twist of the canister rotated somewhat to achieve a good seal. Crack the throttle and turn the engine for a few minutes with the HHO mixture while observing for oil leaks around the filter canister; turn off the engine and add engine oil as desired to cover for required oil quantity needed to fill the filter canister.