We not only cant agree on oil, (because it probably doesn't matter much with todays synthetic oils) but it seems we almost get as many different opinions on what 80:1 gas to oil ratio means in terms of how much oil to add to 1 gallon of gas.
I guess thats why I use 100:1 in my GG - keeps it simple! If a US gallon is 128 oz then: for 80:1: =128/80 = 1.6 ounces of oil in 128 ounces (1 gallon) of gas.
said another way, 1.6oz is 1/80th of a gallon.
likewise 100:1 = 128/100 = 1.28 ounces of oil per 1 gallon of gas.
75:1 = 128/75 = 1.7
50:1 = 128/50 = 2.56