If you are just going for smell, just put a half gallon of any leaded 110 in the tank and call it a day. Having been on a full race gas sled for many years, the smell of straight 110 or 100ll (av gas) can be a bit much. 1 gallon a tank and you will get the desired smell, for just a few ($4-$5) a tank. Whatever you can find at a convenient pump.