I think McD's uses liquid oil, so not hydrogenated (trans fat). You hydrogenate oil to make it solid at room temperature, as a substitute for animal fats. If yo

I think McD's uses liquid oil, so not hydrogenated (trans fat). You hydrogenate oil to make it solid at room temperature, as a substitute for animal fats. If you're going to fry in it there's no point in not starting with an oil that is liquid at room temperature.