the rear main oil seal is the gearbox side behind the flywheel and the front i would assume is behind the crank pulley....mine was leaking oil out really badly which fooked ma clutch...it wasnt that bad to change, u have to take the gearbox off and the clutch and flywheel then i had to remove part of the thermostat housing to allow u to take the lower timing chain cover off. if u havnt had ur chains and guides done now would be the time as its all in front off you and also the clutch aswell seen as its off it took me 2 days to do all of this only replaced all of that as it made sense instead o