Sure, grapefruits have slightly different taste if they are different color, but it is just personal preferences.
I have done it with yellow grapefruits, red grapefruits, lemons, oranges, limes, and it works regardless of the type of fruit you use.
Have read about people doing it with pineapple juice, apple juice, granat apple juice etc.
Juice is there to help you digest huge amount of oil.
Different people have different preferences when it comes to what juice aids digestion, or what juice is available in different parts of the world.
If you can easily get red grapefruits, sure use it. If you can get any other grapefruits, use it. But if you can not get grapefruits where you live, use lemons, or limes, or oranges or pineapple or any other fruit juice slightly acidic taste.