I have a gravel driveway and dump it there. Not very environment friendly I know. Any old oil I have is burned to heat my son in laws shop but I don't like mixing very much gas in it. You might take it to a recycling plant?
Ditto down here.
Old fuel goes into "er" car.
As it is computer controlled it can burn almost any liquid fuel and by the time you put a gallon or two into a 5 gallon tank the dilution factor is so low as to be functionally not there.
my vehicle runs 100% LPG before you ask why I inflict this on my other half.
I just pour it into the mower tank and use it as any gas. Yes, it's in theory not good for the carburetor but I clean my carb at end of every season when I change oil, clean the deck and etc. I honestly don't see the effect of occasional old gas when cleaning the carbs. I've used gas sitting in my neighbor's can for over 6 months.