Castrol Optigear EP Range are mineral oil based high performance gear oils containing Castrols advanced gear oil system which gives special plastic deformation (PD) and surface improvement characteristics. Performance is further enhanced with the inclusion of high load carrying additives which mean optiumum load carrying for both gears and bearings. Optigear EP exceeds the minimum requirements according to DIN 51517, part 3, CLP gear oils and also meets the FZG "Sprungtest" included in the GL5 specification.