Basically, to get the mix spot on, you're best buying the 19L drums (a 20L drum filled to exactly 19L by the manufacturer), at $3.50 per litre. Then put exactly 19 litres of u98 into another drum and pour both into the tank.

In a 205L drum its $2.50 litre.. then you need to work out a way of getting identical quantities of each fuel into the tank.

Maybe I'm just being pedantic, but I don't believe there is a good way of measuring exacting quantities short of eyeballing a fill line on a jerry can. I wouldn't trust my motor to that!

If you can find an easy and accurate method, then it will work out. Either way, mixing is a pain... Straight e85 pumped in via drum pump ftw