3 very interesting links and viewpoints:
It really seems the Tutoro is the way to go. As it gives off about a drop a minute when you ride, and only when you ride. Full stop in traffic-jams during rush hour or in front of traffic lights it does not give off any oil (or perhaps 1 drop). The Scottoiler connected to the engines vacuum would give off oil whenever the engine runs.
With Cobrra, Osco and Loobman, once the plunger is pressed or pulled or swiveled a quarter turn, oil will come, and relatively a lot of oil all at once, so you need to be driving at a given speed for it to work properly. If you need to stop shortly after activation, oil will run off the sprocket/chain onto either the ground or your tire.
Also the timing of a certain amount of oil every once in a while is better than using spray bottles, but dosage is more accurately administered with the Tutoro, 1 drop a minute, only when you drive. And in heavy rains one can adjust say 1/4 or 1/2 turn more oil/drips per minute.Read more