Also Vince when I 1st got my P-51 from my Uncle it had sat for 20 yrs . I had to replace all the old neoprene fuel line , Also the old felt filter membrane . Replaced it with Walbro reproduction element . I found that a half tank of evaporust & a 1' length of dog chain links left in the tank & shaken daily for a few minutes broke up & dissolved all the fuel tanks internal rust in 3 days . It was like a shiney nickle brother
Por -15 also has a very similar product . Both products will not harm non rust laden carbon steel or aluminium or rubber or plastics for that matter . I love my Pioneers , I start & run all 3 of them every year for sentimental reasons . Nothing like the sound of old school Pioneer just off idle to make you feel alive !