This is 135. I've been working for a couple of air ambulance outfits and in 2 of them I was responsible for filling the O2. I changed to a new company this year and they have maintenance do it. But I was never told to write it up. It's actually one of the mechanics daily jobs to refill the tanks on both the med bed and the crew so it never has a need for me to ask or write it up. I beat them to doing my preflight one day and found it down so I asked for a top off and apparently because I asked instead of them just doing it as the normal procedure it's now a write up.