Lubrication System Oil Level Check Cleaning the Oil Tank Oil Change Always allow engine to cool down to ambient temperature  before starting any work on the lubrication system. Severe  burns and scalds may result from hot oil coming into contact  with the skin. Switch off ignition and remove ignition key. To  assure that the engine does not turn by the starter, disconnect  the negative terminal of aircraft battery. Before checking  the oil level, make sure that there is not excess residue oil  in the crankcase. Prior to oil level check, turn the propeller  several times by hand in the direction of engine rotation to  pump all the oil from the engine to the oil tank. This process  is completed when air flows back to the oil tank. This air  flow can be perceived as a gurgling noise when the cap of  the oil tank is removed. The oil level in the oil tank should  be between the two marks (maximum/minimum) on the  oil dipstick, but must never fall below the minimum mark.  [Figure 11-31]  Replenish oil as required, but for longer  flights, replenish oil to maximum mark to provide for more  of an oil reserve. During standard engine operation, the  oil level should be mid-way between the maximum and  minimum marks a higher oil level (over servicing). Oil can  escape through the venting (breather) passage. It is advisable to check the oil level prior to an oil change, as  it provides information about oil consumption. Run engine  to warm the oil before beginning the procedure. Taking  proper precautions, crank the engine by hand to transfer the  oil from the crankcase. Remove the safety wire and oil drain  Cleaning the oil is optional and requires venting of the oil  system. It is only necessary to clean the oil tank and the inner  parts if there is heavy oil contamination. The procedure for  cleaning the oil tank is shown in  Figure 11-32.  Detach the  profile clamp (2) and remove the oil tank cover (3), together  screw (1) from the oil tank, drain the used oil, and dispose of  as per environmental regulations.  [Figure 11-32]  Remove  and replace oil filter at each oil change. It is not necessary  to remove oil lines and other oil connections. Draining the  suction lines, oil cooler, and return line is not necessary  and must be avoided, as it results in air entering the oil  system. Replacement of the oil filter and the oil change  should be accomplished quickly and without interruption  to prevent a draining of the oil system and the hydraulic  tappets. Compressed air must not be used to blow through  the oil system (or oil lines, oil pump housing, oil bores in  the housing). Replace the oil drain screw torque and safety  wire. Only use the appropriate oil in accordance with the  latest operator’s manual and service instruction. The engine  must not be cranked when the oil system is open. After the  oil change is accomplished, the engine should be cranked by  hand in the direction of engine rotation (approximately 20  turns) to completely refill the entire oil circuit. Figure 11-32.  Oil tank.  Figure 11-31.  Oil dipstick minimum and maximum marks. 11-21 Max Min 2 4 5 6 7 8 1 3 CODE 1 2 3 4 Oil drain screw Profile clamp Oil tank cover O-ring Baffle insert Partition Sealing ring Oil tank 5 6 7 8