Sierra 118-9421CAT-7 10W-30 Synthetic Blend Catalyst-Compatible 4-Stroke Marine Engine Oil 7-Quart

The Sierra 118-9421CAT-7 is a 10W-30 synthetic blend, catalyst-compatible 4-stroke marine engine oil packaged in a convenient 7-quart container. Formulated specifically for the demands of the marine environment, this oil meets the requirements of modern 4-stroke recreational engines with or without emission catalyst systems, making it a versatile choice for outboard, sterndrive, and inboard applications.

Key Features:

• NMMA FC-W and FC-W Catalyst Compatible certified — meets or exceeds all 4-stroke marine oil specifications
• Synthetic blend formula with premium base stock and highly refined additive package
• Capitalizes on ZDDP anti-wear additive technology for industry-leading wear protection and deposit control
• Prevents phosphorous depletion to extend emission catalyst life
• Provides superior corrosion protection under extreme marine conditions
• Approved for all 4-stroke applications: outboard, sterndrive, and inboard engines
• Specifically recommended for Mercury 4-cycle outboard engines requiring 10W-30, including 3.4L V7 and 4.6L V8 models, Pro XS, Verado, and Sea Pro series
• Meets or exceeds requirements of major marine engine manufacturers including Mercury, Yamaha, Johnson/Evinrude, Suzuki, and Honda
• 7-quart container — ideal for bulk oil changes or shop use

Sierra's 10W-30 catalyst-compatible marine oil is engineered to outperform conventional automotive oils in the demanding high-RPM, high-load conditions unique to marine use, delivering reliable protection across a wide range of 4-stroke powerplants.