Castrol Brayco™ 599 is a specially designed synthetic base, dark amber, rust preventative concentrate. Brayco 599 is designed for use as an additive for turbine engines and helicopter transmissions which use MIL-PRF23699 lubricating oil. Brayco 599 should be added to the oil sump immediately after an oil change when the equipment is intended to be placed in storage, especially in locations where high humidity and salt spray are present. This fluid should only be used for a limited time, not exceeding 25 hours. Consult the engine manufacturer's manual to determine specific engine model recommendations and/or limitations.