Pay attention to the color of the oil first.… Distinctly creamy, with a pleasant yellowish tint, the color is achieved exclusively with the help of dyes (and this is the fault of advertising, which for years has been driving the rule “real = beautiful” into our poor heads; manufacturers just follow our lead). Real butter is much lighter, almost white, but not snow-white, but somewhat pale yellow. However, dyes don’t make the oil worse. Just keep in mind that you are being manipulated.
Leave the oil cold at room temperature. The more vegetable fats it contains, the sooner it becomes soft. Real butter stays firm for about half an hour. If butter can be spread on bread five minutes after the freezer, then, know, it’s margarine! Even with the most natural taste in the world.
Cut off a piece of butter, place it in a preheated skillet. See how it melts. An abundance of foam indicates a too high content of milk whey and an underestimated content of milk fat. You can eat such oil, but it is not recommended to use it for baking.