Ducati Monster 796 Workshop Manual page 519

Lubrication system: oil cooler
Drain the oil from the lubrication
system
Loosen the screws (12) and remove the deflectors (11) and (14) and conveyor (13).
Loosen screw (9) to remove hoses from cable grommet (10). Release tabs (B) from cover (C).
Loosen the nuts on the unions (A) and detach the supply (6) and return (5) pipes from the cooler.
Check the condition of two O-rings at each hose connection.
4 - 3, Changing the engine oil and
filter cartridge