Quicksilver 25W-40 4‑Stroke Marine Engine Oil - 1 Gallon, FC‑W Rated for Outboards & Sterndrives

Quicksilver 25W-40 4-Stroke Marine Engine Oil is a full‑sized, marine‑spec lubricant engineered to protect sterndrive and outboard 4‑stroke engines under high‑RPM and corrosive saltwater conditions.

Keeping engine oil clean and suited to marine demands is essential for long service life and reliable performance. This Quicksilver 1‑gallon formula meets and exceeds marine 4‑stroke standards, including FC‑W and catalyst compatibility, and is developed to match Mercury Marine equipment specifications. The result is a single product designed to resist corrosion, minimize internal wear, and support high‑rpm outboard operation.

How does this oil protect engines used in saltwater environments?

This Quicksilver blend includes additives tailored to reduce corrosive attack on metal surfaces and to keep internal parts lubricated under marine conditions. It forms a resilient protective film that shields components during idle and high‑load operation.

• Corrosion inhibitors formulated for marine exposure
• Anti‑wear additives that preserve bearings and cam lobes
• Stable additives that resist breakdown from heat and humidity

Will it work with my Mercury Marine outboard or sterndrive?

Yes—this oil is produced to meet Mercury Marine OEM specifications and serves as a direct replacement for Mercury part 8M0078628. It’s compatible with most 4‑stroke outboards and sterndrives that require 25W‑40 viscosity and FC‑W level protection.

• Direct replacement for Mercury Marine 8M0078628
• Meets Mercury Marine original equipment requirements
• Suitable for many 4‑stroke outboards and sterndrives

What performance benefits does 25W‑40 viscosity deliver for high‑RPM motors?

The 25W‑40 grade balances cold‑start flow with high‑temperature film strength, helping engines maintain oil pressure and reduce metal‑to‑metal contact at elevated RPMs. Special viscosity modifiers help the oil stay within optimal thickness across a wide temperature range, supporting consistent lubrication during varied operating conditions.

• Optimized film strength at high operating temperatures
• Viscosity modifiers to support stable oil thickness under load
• Enhanced protection during sustained high‑RPM runs

How does using Quicksilver oil simplify maintenance and parts compatibility?

Choosing Quicksilver helps streamline upkeep because the formula is designed and tested alongside Mercury equipment and other marine systems. That alignment reduces the risk of compatibility issues with seals, catalysts, and engine components while simplifying parts sourcing.

• Manufacturer part number 8M0078620 for easy identification
• FC‑W and catalyst compatibility minimizes system conflicts
• Formulation tested for common marine service conditions

Who is this for? Boaters and marine technicians who demand OEM‑level lubrication for 4‑stroke outboards and sterndrives will benefit from Quicksilver 25W‑40. It’s suited to owners of Mercury Marine equipment looking for a direct replacement, as well as operators of other marine brands who need a durable, corrosion‑resistant oil engineered for high‑RPM performance and long‑term reliability.