Fuel/Oil/Coolant line markings

These all appear to be “snap on” labels, so no adhesive needed.  And yours is not a terrible idea, as long as you get the initial placement correct. I, too, spend a lot of time when the cowling is off tracing the flow of fluids before I do anything under there. 

Way back with my first 912, I did the same thing - used "White Out" as a marking pen. Seems to be heat tolerant can be found in most if not all stationary supply shops.😈