Gilsonite is used as FLUID LOSS CONTROL (gilsonite drilling muds) additive or FLC in Oil based drilling muds (OBM). It can be applied according to its hydrocarbon nature and the proper softening point to cause a significant decrease in the loss of fluids during the drilling process. The Gilsonite Solubility in Oil matters (measured by solving in TCE, CCL4 & CS2) allows the additive to act well with the oil material of the drilling mud, in most cases diesel. Also, same characteristics results in composition of Gilsonite powder in synthetic based muds (SBM) since the base material is a polymer. . The current grades of American Gilsonite in the Oil drilling sector are: Gilsonite XM-P, Gilsonite GM-P, Gilsonite LM-P and Gilsonite HT series which have equivalent supply of Iranian Gilsonite.