You ARE using it through the valve guides. There probably is not a greater statistical diagnosis in the automotive world. Those motors just never have ring problems.
Its either on the ground or out the pipe. Amazing thing those catalytic convertors. Before them the blue smoke would have been there at idle and after a long deceleration. Now as with other unburned hydrocarbons they are scrubbed up in the exhaust. Oil consumption in your range is easy for the cat to cover for a while. The carbon build-up will eventually take out the cat.
Bosch Master, ASE Master, L1
33 years MB technician