MG RX9 Transmission and Driveline Fluids: 2WD and 4WD

What the automatic's fluid does

In a torque-converter automatic, the fluid transmits engine power through the converter, applies the clutch packs that select each gear, lubricates gears and bearings and carries heat to the cooler. A fluid with the wrong friction or viscosity changes how firmly the clutches engage, which shows up as slipping, flare between gears or harsh shifts. That is why only the fluid MG lists for the RX9 gearbox should go in.

What the 4WD grades add

On the COM 4WD and LUX+, drive also reaches the rear wheels. That usually means a coupling or transfer unit, a propeller shaft and a rear differential. MG's published material doesn't say which of these has its own oil or how often it is changed, so ask for them by name at a major service on a 4WD car.

Tyres and the 4WD system

On the 4WD grades, mismatched tyres front to rear make the axles turn at slightly different speeds, which the 4WD system then has to absorb. Replacing tyres as a set, or at least by axle with the same size and brand, protects the driveline as well as handling.

Symptoms worth reporting

Possible causes only; diagnosis needs a workshop.

Ask before a gearbox service

• Which fluid MG lists for your RX9 gearbox, and how much is needed.
• On a 4WD car, whether the transfer unit and rear differential are due.
• Whether the gearbox needs an adaptation reset afterwards.

Fluids and driveline parts for an RX9

Tell us the grade on your registration or the badge (2WD or 4WD) and send the VIN. We confirm each fluid MG lists for your version and can quote parts such as the automatic gearbox or axles once your workshop has diagnosed a fault.