What oil can you use to silence a whining diff?

To silence a whining differential, you can use a high-quality gear oil specifically designed for differentials, such as synthetic gear oil with a suitable viscosity rating (commonly 75W-90 or 80W-90). Look for products that contain additives like friction modifiers to enhance performance and reduce noise. Always consult your vehicle's manual for the manufacturer's recommendations to ensure compatibility. Regular maintenance and checking for proper fluid levels can also help reduce whining sounds.