FWIW back in the 80's working at a dealership I had a customer vehicle using a qt of oil every 100 miles, no visible smoke, ran fine, just used allot of oil.. I tore the engine down & found one cylinder had no oil ring.... So one cylinder was using all that oil, the plug didn't look oily, it had a little fluffy tan powdery residue but no black goo....
People expect this....