i have used motul 8100 and found it to be a better oil than the mobil 1, the mobil 1 lost viscosity after 1000kms...... not a good oil, good for NA but cant handle the heat of the turbo.
i havent had a prob with the filter in mine, use some sandpaper to undo it and also when the car is cold not hot or you will burn yourself. it will undo easy with the sandpaper and then just manouvre it out
the filter number from nissan is 15208-53j00 and its the same for the N14 gtir, S13 silvia, U12 and U13 SR20DET's, dont use a s14 or s15 one as they are different, although they may appear to mount up all the same they may flow different so not advisable to use