Using a prog called "Glowcalc" (glow fuel volume ratios):

Methanol 59% = 0,59 US gallon = 75,52 US fluid Oz
Nitro 30% = 0,30 US gallon = 38,40 US fluid Oz
Oil 11% = 0,11 US gallon = 14,08 US fluid Oz
Total 100%

Methanol 59% = 0,59 US gallon = 75,52 US fluid Oz
Nitro 30% = 0,30 US gallon = 38,40 US fluid Oz
Oil 13% = 0,13 US gallon = 16,64 US fluid Oz
Total 102%


Difference = 2,56
So you were correct