As MR. Gadget suggested. Let most of it run out of the top(Vent) fill plug. The level should be jsut to the top of the vent/fill plug. This is the proper fill level for the drive. Make sure the drive is level whe nyou do it as well. The bottle is an expansion tank not a reservoir

You can put an once in the bottle to give a little extra. Thats it. Run it again and keep an eye on it.

Make sure your shower is not clogged and spraying correctly as well.

I went out Sunday, still not running the boat hard since its a brand new motor and drive. Still had fluid come up into the expansion tank probably close to 2" and I was only running about 35-45 mph. I am not running a drive shower as of now.

Get a drive shower. Will definately help.