Rover service publications – implying it was an 8-valve version of the M Series engine, although it was identical to the O series used in the Maestro and Montego. Diesel versions In 1986, BL collaborated with Perkins to convert the O-series to run on diesel. The oil-burning versions, known as the Rover MDi or Perkins Prima, proved to be highly successful in the Maestro and Montego, and helped sustain the ailing mid-sized models into the 1990s. Perkins successfully marketed the engine under its own brand in the industrial and marine sectors. Examples of vehicles using a version of the O-series engine: Austin Maestro 2.0 L, 2.0 L Diesel Austin Montego 2.0 L, 2.0 L Diesel Leyland Sherpa/Freight Rover Sherpa/200/300 1.7 L, 2.0 l Princess / Austin Ambassador 1.7 L, 2.0 L Morris Ital 1.7 L, 2.0 L automatic Morris Marina 1.7 L Rover SD1 2.0 L Rover 820 2.0 L MG Maestro 2.0 L MG Maestro 2.0 L, turbo MG Montego 2.0 L MG Montego 2.0 L, turbo Naylor/Hutson TF 1700 References O-series engine story O BMC engines Gasoline engines by model Straight-four engines