Tried using this USB fluid transfer pump with the coolant. It has a soft hose to dump fluid and a skinny hose (with a section of soft hose as the lead) to draw fluid. It would have fit into any narrow diameter opening that is damn STRAIGHT.
The radiator cap sits on a short arm that extends from the radiator itself. The skinny hose is a bit too stiff to get in the L. I was only able to draw a small amount of coolant out. It was enough for me to add two oz of cooling agent. My other two street cars are both running distilled water mixed with cooling agents.
Then I tried to draw from the reservoir. Again, it is not a STRAIGHT shot from the cap, there's some barrier blocking the way. I tried aiming for the gap before poking the skinny hose randomly, hoping that it'd squeeze by the barrier. It worked and I got almost everything out from the reservoir. I don't think Mazda engineers wanted us to do this from the top.
I believe the pump will work with engine oil and ATF. I know that the ATF port to pan is straight. I hope there's nothing tricky down the oil dipstick hole. The skinny hose might not be able to pick up chunks of sludges though, if there's any.
How do you clean the pump? I was thinking if I have to buy one pump for each fluid (I.e., oil/ATF/coolant). I can also just pump a small amount of the different fluid to run it through and then dump that fluid. It's hard to tell how much fluid remains in the pump itself. The hose are easy.
My next ATF drain/fill will be with this pump.