How do you fill the transmission oil on a 2004 fatboy?

To fill the transmission oil on a 2004 Harley-Davidson Fat Boy, first ensure the motorcycle is on a level surface and the engine is warm. Remove the transmission filler plug, typically located on the side of the transmission, and use a funnel to pour in the recommended transmission oil until it reaches the bottom of the filler hole. Replace the filler plug securely. Always check the owner's manual for specific oil type and capacity.