For a 2000 Mercury Mountaineer, the recommended differential oil is SAE 75W-140 synthetic gear oil. This oil is designed to withstand the high temperatures and pressures that occur in the differential, and it will help to protect the gears and bearings from wear and tear.
It is important to use the correct type of oil in your differential, as using the wrong oil can damage the components. If you are unsure of what type of oil to use, you can consult your vehicle's owner's manual or a qualified mechanic.
