For practical purposes mix your gly at the proper rates and spray away! A surfactant increases the odds of getting the kill you expected. Do all brands of over-the-counter gly contain surfactants? I bought some that did not. I bought it because it was cheap(er). My mistake. You know what they say about assumptions! I would assume if the gly you buy does not say it contains surfactant, personally I would add some at .25% to 1% of the finished volume. I could be wasting my money. But, I don't want to spray twice. Roll the dice?
Dish soap. Again, it probably works like a surfactant but its formulated to clean dishes and not to substitute as a surfactant. Long ago and far away advice was it could be a substitute, but dish soap formulations have changed and I read some can change the molecular structure of your herbicide leading to decreased performance. Your call.
Crop oil vs surfactants? I think there's still some scientific mystery here. Read your label and use whatever it recommends. The herbicide researchers have used both in trials and, if one helps the herbicide work better than the other that's what you'll see on the label. If no surfactant or crop oil is specified then neither provided any benefit. While I/we write as if these things are absolutes, they are not.
Again, I realize these are fine points only offered for consideration.
