Some techs tell You just fill it to the line and QF is enough for that. When I have a over zealous tech who just hands it to Me and says fill it up, I come out of the bathroom and before they can even say a word I say I'm sorry I could only go this much. I just don't go like I used too or I joke and say 10 years ago I would have filled 10 of those. (I'm in My 50s) There reply is always thats fine.