First things first: Either is always paired with or, and neither is always paired with nor. If you are matching either and nor, I hate to break it to you, but you’re doing it wrong.
Correct use for Either: Either is used when you are making a comparison between two ideas, and only one of the ideas will come to pass. Example: "either multinational or transnational may have the same meaning" the two options are correct, but both hace the same meaning, so you have to choose one.
Correct use for Neither: Neither indicates that the two ideas are linked together. It’s kind of like a negative conjunction. But if you use neither, then make sure your sentence does not have any other negatives preceding it. If you prefer to use a negative, then you want to use either. Example: "neither the fuels nor the oil business itself would be so successful without this companies."