Hello All! My Deceased Speed-Flying partner, Larry "BEBOP" Stockstad used to polish the pans on a buffing wheel, and then spray-coat them with the material he used for all the Brass Band instruments that he repaired for a living. It DIDN'T hold up for too long with the 70 % Nitro we used back in the 80's, but should do better with the 10% Soda-Pop we're using now for fuel.
A trip to a Musical Instrment store, that does repairs to Brass Band instruments for School Bands, would get you the type of material they're using now to keep the horns nice and shiny.
Cheers, Glen