A method and a system for lubricating a turbine engine including at least three separate housings each including at least one roller bearing. The method pressurizes the housings through seals, of which two main housings are pressurized at a pressure higher than that of a remaining secondary housing, lubricates a secondary roller bearing only by injecting an oil mist from at least one of the main housings, the oil mist being supplied by a pressure difference between the main housings and the secondary housing, recovers a remainder of the lubrication oil injected into the main housings to supply the same to an oil tank, and supplies the air/oil mixture from the secondary housing to an oil separator.