Some people have no problem taking that much oil, but many simply throw up with it. There are a number of extreme cleanses out there, and if you feel pulled to trying it out, do it. I personally favor the steady, more gentle way of cleansing the liver. It can be quite a challenge for the body to deal with that much oil.
Ususally, it is due to AMA (see The key to Health and Rejuvenation)moving up from the intestinal tract towards the mouth during the night and blocking proper moisture supply to the tongue. With digestion and eliminative functions contineu to improve, this should become resolved. Heating the bedroom during the night can also cause this condition.