After developing a similar device for the U.S. Navy in the 1980s, Walker Engineering introduced the AirSep Air/Oil Separator to the recreational marine market, and in 1989 it quickly became standard equipment on Detroit Diesel engines. In 1992, Caterpillar made them standard on certain models, including 3116, 3126, 3406, and 3412, as did Alaska Diesel. Cummins followed suit in 1994. And as the engines have evolved, the AirSep has changed with the times. They now have a more effective silencer feature, but the basic technology has remained the same.