How do you tell what kind of oil you put in your differential?

To determine the type of oil for your differential, check your vehicle's owner’s manual, which specifies the recommended viscosity and specifications (like API rating) for differential fluid. Additionally, you can inspect the differential cover for a label or sticker that might provide this information. If you're unsure, consult with a mechanic or a dealership for guidance based on your vehicle's make and model. Always ensure you use the correct type to maintain optimal performance and avoid damage.