I work part time at a local airport. We sell a lot of 100 octane low lead avgas (100LL) this time of year to boat owners and people putting up their power equipment for the winter. I run this in my Briggs and Kohler engines. The Honda engines don't like the lead. The local old car museum sends a pickup with 5-35 gallon drums in the back every spring. The stuff has a shelf life stated at 2 years, but we regularly pull planes out of hangars that have been sitting for years and typically they start right up after a battery charge. Local mogas $2.30, 100LL $5.25.