I opened up my sealed gasoline vessels today. They are old propane cylinders that I capped off after putting gas in IN 1999. After testing a small amount for volatility, I poured several gallons into the small gas tank on my Toyota thus mixing it with fresh gas. I drove it about 25 miles and it runs the same way it did before. I have no way of telling what the remaining octane is, but the good news is that it is USABLE. I plan on mixing a gallon of fresh premium with about 2.5-3 gallons of the stale before dumping it in the fuel tank in subsequent fillups. S V