stable water - in - oil invert emulsions suitable for use as fire - resistant lubricants and as fire - resistant hydraulic fluids of improved extreme pressure properties are disclosed . a mixture of polyisobutenyl succinic anhydride , a member selected from the group consisting of a vegetable or animal oil or a mixture thereof , and a mono alpha - unsaturated olefin is sulfurized under heat . the sulfurized mixture is then reacted with a hydrophile on an equivalent basis . this compound is then blended with suitable base stock to form an invert emulsion with improved e . p . and anti - wear properties .