Then let me clarify.
The act of opening and closing a quick access panel for the purpose of a fluid level "check" is not maintenance. Under the regulations a pilot of the aircraft may check fluid levels, even if this entails opening and closing quick access panels.
That's not to say that it is practical for all operations, but it is permitted.
The act of "inspecting" against a specified criteria for the purpose of determining serviceability (inspecting oil level and calculating consumption rate per AMM requirements) is clearly a maintenance activity. The check of oil level as described in the earlier paragraph is also maintenance if it forms part of the approved maintenance program for the aircraft (Daily or similar level maintenance pre-flight checks).
MP.