To find it, you'll need to:
1. Consult your owner's manual: This is the best and most reliable source. It will show you exactly where the fill plug and drain plug are located, and what type of gear oil to use.
2. Look underneath the rear differential: The differential is usually located near the rear axle, often towards the center of the rear of the vehicle. The fill plug is usually a bolt or a similar fitting on the top or side of the differential housing. It may be marked, but not always clearly. Sometimes it's close to the drain plug.
3. Use an online repair manual or forum: If you don't have the owner's manual, a repair manual specific to your car's make, model, and year will show you diagrams and instructions. Online forums dedicated to your car model can also be helpful, as other owners may have posted pictures or discussed the location.
Caution: Be extremely careful when working under a car. Secure it properly on jack stands and never rely solely on a jack. Wear safety glasses and gloves. If you are unsure about any aspect of this process, it's best to take your car to a qualified mechanic.
