John B. wrote:

On Thu, 8 Dec 2016 15:11:55 -0800 (PST), wrote:
On Tue, 21 May 2002 18:25:22 -0500, "Ronald Thompson"
wrote:

Around here (Southern Ontario) the srug stores sell 99% Isopropyl
alcohol as "Rubbing Alcohol," which should do it nicely. The the
70% alcohol / 30% water mix is called "Rubbing Alcohol Compound."

I'm definitely not a chemist, but the presence of alcohol usually accompanies corrosion.

"The alcohol attracts water, leading to increased corrosion in
metal gas tanks". (its a quote commonly found on the internet)

They used to sell some stuff called "dry gas" to remove water
from automotive fuel tanks. It was simply alcohol. The alcohol
mixes with the water which makes a combustible mixture and is
burned by the engine. In fact the gasoline/alcohol fuel blends
will absorb some water normally.

Before the water leaves the tank, I guess the rust or other debris from any corrosion remains.