Securing the fastener on the gas tank lvl sensor.
 

I recently removed/cleaned and inspected my fuel tank level sending unit. During disassembly I scraped off the "varnish" like substance that was being used to prevent the nut from turning that is on the treaded rod that keeps the unit together. I need to know what I can put back on the nut to make sure it does not come off. Would nail polish work submerged in gasoline, how about varnish. This was on the E320. thanks

Use RED Loctite and let it cure. It will not desolve once dry.

Curious to know if cleaning the wires fixed the problem ?? Let me know.

I'll pull it and put some red loctite on it this afternoon. Funny thing was that it only happened one time at about 1/4 tank. Once I put some fuel in it I have not seen the problem again - even after running it back down through a 1/4 tank.