Originally Posted by StuM
It's not just the size - the cap has a standard winch
handle keying instead of those PITA "slot with a small hole at each end" which requires a dedicated key or a jury rigged opener.
Except that the socket in the cap isn't deep enough and the shaft on the winch handle has both a twist lock on the tip, plus tapered tip, so mostly what happens is the winch handle slips in the cap socket and both get worn out. This is what I'm dealing with now and have to use the two-flathead-screwdriver-technique to open the caps
I'd need to get a proper flush ended winch handle in order to not have this problem, which takes me right back to having a dedicated "slot with two holes" tool. Never ending cycle.
Next problem is the deck fill spout is a polymer, so the cap can not be metal or I'll risk stripping the spout. Maybe something to change out later, but I'm in no hurry there.