Stop fighting with your Mercury engine. This factory-spec OIL TANK ASSEMBLY eliminates common issues and delivers the smooth operation you expect from genuine OEM components.

Built with Mercury Marine’s precision engineering, this component ensures reliable operation across all engine RPM ranges. Part number 812778A1 is manufactured to exact Mercury Marine factory specifications for precision installation and optimal performance. Constructed from premium marine-grade materials designed to withstand harsh saltwater and freshwater environments.

Factory parts exist for a reason — they work. Part 812778A1 undergoes rigorous Mercury Marine quality testing that aftermarket manufacturers skip. The result? Reliable performance season after season.

Compatible Mercury Marine Engines

FITS: 30-40HP MARINER, MERCURY

• Fits MARINER, MERCURY 30-40HP engines
• Compatible HP: 30HP, 40HP
• Covers 8 serial number ranges
• Configurations: Jet Drive, Outboard
• OEM genuine Mercury Marine part

COMPLETE SERIAL NUMBER COMPATIBILITY:

30HP Models

• 30HP JET (Mariner): 0C159200-0G589999
• 30HP JET (Mercury): 0C159200-0G589999

40HP Models

• 40HP OUTBOARD (Mariner)
• 40HP OUTBOARD (Mercury)

Looking for your Mercury engine serial number? Our helpful guide shows you exactly where serial numbers are located on different engines.

Verification & Support

Not sure if part 812778A1 fits your engine? Try our parts finder tool — it’s quick and easy. Need expert help? Contact us using the buttons at the bottom of this page – text, call, or email, whatever works best for you

Trusted marine parts specialist since 1985. Great prices, quick delivery – your parts ship fast.