Mercury Owners Manual - 90-825757D50. The Mercury Owners Manual - 90-825757D50 is the official factory guide for understanding, operating, and maintaining your specific Mercury outboard engine model. Created by Mercury Marine, this manual provides straightforward, reliable instructions to help you get the best performance and longevity from your engine-whether you're new to boating or a seasoned operator.. Key Features. Authentic Mercury Marine Manual - Printed and distributed by the original ma