MANY THANKS TO ALL OF YOU FOR YOUR ADVICE. I WILL TRY PLUS GAS OR PENETRATING OIL TOMORROW TO REMOVE CISTERN WINGNUTS (HOPEFULLY). WILL LET YOU KNOW IF IT WORKS.
TRYING TO REPLACE FLUSH VALVE ON WC CISTERN. PROBLEM IS I CAN'T REMOVE WING NUTS. BOTH BADLY RUSTED AND ONE IS EVEN MISSING THE WINGS. CAN'T GET AT THEM TO SAW OFF SO REALLY STUCK!! CAN ANYONE ADVISE PLEASE. DON'T WANT TO HAVE TO CHANGE THE SUITE.