Dorsal,
I have "vintage tanks" in my aircraft and am waiting for the brown goo. I have been fortunate to have one gas station that still carries no ethanol but at the end of the year it is "curtains" ! The law mandates it in our state. Am holding off on the alcohol for as long as possible.
One other indication of a problem with that goo stuff is no compression as you turn the prop to burp your engine. The goo can coat the intake valve valve guides and stick the valves.
I have installed wing filters to check for flaking of the sloshing compound and I thought break down of the resin but I guess that won't work.
Am still thinking about the best solution if and when breakdown of the resin does occur. I probably will pull the wings remove the tanks and install the new ones that John offers..don't know yet.
Dick
912UL
Milton,Fl