The size can I use is 16 oz. I've been dumping 1/2 the can in, then fill up with gas for storage. I put a few miles on just to make sure it has reached the carbs. I think the label says use more to clean -- less to maintain. Never had any fuel related issues to date (knocking on wood). I've found that Stabil will over time separate and form little granule like globules of something in the bottom of the bottle. I noticed that five or six years ago as I was dumping the remaining contents of Stabil into the gas tank. Removed the tank/petcock and cleaned it all out, then did it again . . . with Sea Foam. Ymmv,
ditto for me - 1/2 a can to a full tank of fuel, then ride enough to get it through the system. I also then shutoff the petcock and run the engine till it starves and dies. Have never had fuel related problems with any of my machines with this approach.
I also have quite using Stabil - found that it breaks down in the bottle if it sits for awhile. Not a very stable fuel stabilizer...