Here's a little story - make of it what you will:
Quite a few years back, an Airworthiness Directive was issued regarding a certain model of piston-engined Piper aircraft. The instruction was to remove the 'Turbo' sticker (or badge, I forget which) from the cowling. The reason: a fueller had filled the tanks with jetfuel, surmising that Turbo meant turbine instead of turbo-charged...
Re the hydraulic/engine oil can debate: In almost 30 years I've never made a mistake with the two but I have made other errors whilst dog-tired, so I'll hold on apportioning blame.