There was a thread sometime ago re Protectan - and propane/butane.
My fist findings using butane (gas lighter refuel bottle):
The paper developer bottle half full would bend towards the inner side without it, due to oxygen absortion by the developper. Now no more (and sometimes even to the ouside, like a barrel, due to excess butane).
The devloper (I use homemade ID-62) looks like new even with just one quarter bottle full after about a week (and before that 3/4, 1/2, etc). It was darker without butane.
I turn the butane bottle upside down and squeese the valve for 1~2 seconds inside the dev bottle and close the dev tight.
All the usual safety precaution apply.