On my motorcycle there is a gas stain on the tank of the bike and it was there when i bought it. I can't post links yet but Now the stain goes down the side about another 5 inches. What should i do to try and get rid of it to make it match with the rest of the bike and to get back its shiny finish? Is it something i can do myself or will i have to take it into a paint shop or something? I just got it out of the mechanical shop a few weeks ago so i don't want to spend much money. Any help would be appreciated