Is Oil a lubrication? Or a preservation?  

Your arguement is "do you log adding fuel"?   Fuel is not lubricant!  Oil is a lubricant.  Lubricants are maintained to prevent engine failure.  If the engine oil is low, it the in an airworthy condition??  What is the planned consumption rate of engine oil in a flight?  Do you have to report it on your flight plan "Oil Endurance in Hours and Minutes"?   No, because it is not expected to be consumed, like fuel is!  

You gave the 1.1 general definition, but Appendix A, (c)(6) specifically says "lubrication" is a preventative maintenance.  

If the transmission oil is low, do you have to write it up?   T/R gearbox?  Rotor Brake fluid??

If it's not preventative maintenance, you are saying ANYONE can do it, including the 16 kid who drives up on his skateboard.   "Hey kid, fill up that transmission for me, will ya?"

Maybe in a Part 91 aircraft, but this is a for-hire commerical operation under Part 135, which prohibits preventative maintenance from being performed by just anyone.  If it is not even preventative maintenance, such person can service your commerical operation aircraft.

If your engine has a oil consumption limitation, the ONLY way you can show you meet that is by documenting the oil you add to the system each and every time.   I have yet to see a fuel consumption limitation.