The Fat Shaft Oil Seal is designed for Mercury Racing and high-performance outboards, specifically fitting 2.5-liter, 3.0-liter, and 3.2-liter Sportmaster, Torquemaster, and Bravo XR/XZ sterndrives or outdrives equipped with 1.25" (1 1/4") big propeller shafts. It is engineered for high-load, high-RPM conditions in aggressive marine applications.
 
This seal is manufactured using high-quality Nitrile Rubber (NBR) lip material and is built to meet or exceed OEM specifications. It offers excellent resistance to petroleum-based hydraulic fluids, gearcase oils, alkalis, acids, and hydrocarbon-based cleaning solvents. Its wide operating temperature range ensures reliable performance in a variety of marine and racing environments.
 
A key feature of this oil seal is its non-magnetic construction, which provides significant advantages in saltwater and brackish water applications. Being non-magnetic helps reduce the risk of corrosion caused by electrolysis, a common issue in salt-rich environments where magnetic metals can attract particles and increase galvanic activity. This enhances both seal longevity and gearcase protection in harsh water conditions.
 
Ideal for use in Mercury Racing lower units, this non-magnetic 1.25" prop shaft oil seal delivers durable, leak-resistant performance for high-speed marine engines and performance boating applications.
 
Includes one (1) Propshaft Seal for the Mercury 1.25 inch Fat Shaft. (Note: The seals are no longer blue as pictured) 
 
Compared to Mercury OEM Part Numbers: 26-815565, 815565