I had a 90w squirter I made when I was working on cars a lot. It is a
freon jug with a hose connection, valve and a tire chuck. Air this
thing up and when you are under the car filling a transmission or
rear, stick the nozzle on the hose in the hole, open the valve and off
you go. I am about to make something similar for putting in L/U oil.
That is always a hassle squirting it in from a bottle and I ended up
making a mess. I have a pump but that is not as easy as it sounds
either. I am thinking the squirter may be the way to go. I am thinking
PVC should work fine.
I already have a bolt the size of a Yamaha drain plug I screw in the
top hole when it is full so you can pull out the filler and put in the
bottom plug. It is easier than screwing with the little drain plug.
Once you get the bottom plug in you can do the top one a lot easier.