I poked around with my endoscope this morning and discovered that filling up the tank still leaves air inside as there still was rust on the top of the tank. I took a radiator hose and cut it off so it would be higher than the top of the tank when attached to the filler neck. I then got some 1/4 inch hose and sucked as much of the air out as I could. I added around 1/2 gallon more of rust911. Other than the very top of the tank it is as clean as a whistle. Wish I had the endoscope when I had the tank out of the car!
