realcarlos,
You want to make sure you are getting Magnesium Chloride.
To make the Magnesium oil...1 cup magnesium flakes and 1 cup water. That is the strength that is sold in stores (liquid form). If you want stronger oil keep adding magnesium flakes up until they don't dissolve any more, that is the highest concentration you can get.
Essential oils and the vitamin E should be added after the oils have cooled, before you whip. Too high a temp and they evaporate.
After it cools again (on the counter - not in the refrigerator) is when I whip the magnesium oil in.
Hopes this helps...how is your Aunt?