Sierra Marine 18-9420-2 Premium Blend 4-Stroke Marine Engine Oil – 10W-30 FC-W Certified (1 Quart)

Sierra 18-9420-2 Premium Blend 10W-30 is the #1 most commonly specified 4-stroke marine oil on the water today. This NMMA FC-W certified semi-synthetic blend is formulated specifically for modern 4-stroke outboards, sterndrives, and inboards — delivering superior wear protection, corrosion resistance, and detergency in both fresh and saltwater environments.

Perfect when your owner’s manual calls for 10W-30 FC-W (almost all newer Yamaha, Honda, Suzuki, Mercury 75 hp+, Tohatsu/Nissan, and many Evinrude/Johnson E-TEC 4-stroke models).

Key Features & Benefits

• NMMA FC-W Certified + meets API SJ / CF-2 / CH-4
• Excellent cold-start flow with 10W protection and stays in grade at high temperatures like a 30-weight
• Superior corrosion inhibitors — ideal for seasonal storage and saltwater use
• High detergency keeps pistons clean and prevents ring sticking
• Advanced anti-wear additives reduce engine wear under heavy loads
• Outperforms standard automotive 10W-30 oils in marine conditions
• Backed by Sierra’s 50+ years as the marine aftermarket leader

Specifications

• Viscosity: SAE 10W-30
• Type: Premium Blend (semi-synthetic)
• Volume: 1 U.S. Quart (0.946 L)
• Certifications: NMMA FC-W, API SJ, CF-2, CH-4
• Sold as: Single quart bottle
• Approximate shipping weight: 2 lbs

Common applications:

• Yamaha 4-stroke outboards (F70 and above, most current models)
• Mercury 75–150 hp 4-strokes
• Honda, Suzuki, Tohatsu 4-strokes specifying 10W-30 FC-W
• Many sterndrive/inboard gasoline engines where 10W-30 is recommended

(No manufacturer warranty — see Sierra’s standard terms)