What type of grease goes in the lower unit of a mercury boat motor?

For a Mercury outboard motor's lower unit, it's essential to use a high-quality marine gear oil specifically designed for outboard motors, such as Mercury High-Performance Gear Lube or an equivalent. These lubricants offer Excellent protection against corrosion, water intrusion, and wear under high-stress conditions. Always check the owner's manual for the specific type and viscosity recommended for your particular model.