It has been answered. Nitro is available up to 100%. Nitro has nothing to do with lubing anything. In fact, nitro is the worst thing in your motor. Its corrosive, it attracts moisture to the steel parts. The more percentage you have the bigger explosion, so you have to lower compression to prevent detonation and knocking.

The big advantage of nitromethane is that you can get a lot more power from each explosion inside the engine. Pound for pound, nitromethane is less energetic than gasoline, but you can burn a lot more nitromethane in a cylinder. The net result is more power per stroke. You typically need about 15 pounds of air to burn 1 pound of gasoline, whereas you need only 1.7 pounds of air to burn 1 pound of nitromethane. This means that, compared to gasoline, you can pump about 8 times more nitromethane into a cylinder of a given volume and still get complete combustion. (web searched)

R/Cs are two stroke nitro burners, there is oil mixed in the fuel you buy. However, the nitro is still there with its properties so it attracts some moisture and its corrosiveness eats on your bearings and parts, so that is why its a good idea to ARO your engine after each days use. The oil doesn't necessarily STICK to the parts in there, it just lubes during use.

My .2cents.