I have been running mogas in my 140 since I bought it in 2013. This year I started seeing bubbles around the rivots on the fuel tanks. Annual time came around and I asked the a&p what the bubbles were from. He told me the tank was leaking. About $2200 later I had the tanks resealed and the guy that did it said the mogas destroyed the sealant. There goes all of my past and future savings not buying 100LL. After this incident I am only running 100LL. Just letting you guys who run mogas know what happened.