Mercury – 10W-40 4-Stroke Marine Engine Oil, 1 Gallon | FourStroke Lubrication Series | Mineral Base Oil | 8M0148477

Overview

Oil changes aren’t the glamorous part of boating, but they’re the part that keeps the whole story going. When you’re miles from the ramp and the water turns unpredictable, you want to know your engine is protected on the inside, not just rinsed clean on the outside. Good marine oil gives you that quiet confidence—like the motor is running smooth, steady, and cared for, even when you’re asking a lot from it.

This Mercury Marine part is the kind of oil you pour in and don’t overthink afterward. It’s built for the heat, the moisture, the long idle at the dock, and the hard run back home. If you’re the type who wants your engine to last, this is one of the simplest habits you can keep.

Key Features

• Four-stroke marine engine oil designed for outboard, sterndrive, and inboard engines
• Mineral base oil with a marine-focused additive package
• Helps protect against corrosion and excessive wear in marine conditions
• Designed to handle heat and stress from high revolutions per minute operation
• Helps protect against varnish build-up and sludge formation
• Viscosity rating: 10W-40
• Meets or exceeds FC-W marine engine oil requirements, including catalyst compatible standards
• One-gallon bottle size
• Mercury Marine part number 8M0148477

Engine & Boat Compatibility

• Suitable for four-stroke marine engines including:
  • Mercury and other four-stroke outboards
  • Sterndrive engines
  • Inboard engines
  • Many personal watercraft engines that specify this grade
• Common on bass boats, pontoons, center consoles, cruisers, and family runabouts
• Always follow your owner’s manual for exact oil type and service interval

Performance & Practical Benefits

You can’t see oil working, but you can feel the results over time. With the right 10W-40 marine oil, your engine tends to sound calmer and run more consistently, especially when the day includes a mix of idle time and long, hot runs. Marine use is tough on oil. You’re dealing with humidity, the potential for salt exposure, and temperature swings that don’t always match car or truck conditions. This oil is formulated for that reality.

The viscosity is a practical middle ground for many four-stroke marine engines. It’s meant to maintain a stable protective film when the engine is warm and working, while still flowing well enough during start-up to protect moving parts quickly. That protective “cushion” matters for longevity. It helps reduce wear where it counts—under load, at higher revolutions per minute, and during those long cruises where the engine is doing steady work.

Another thing boat owners appreciate is cleanliness. Oil that helps control sludge and varnish keeps the inside of the engine in better shape, which supports smoother operation and simpler long-term maintenance. Pair it with routine service and good filters, and you’re stacking the deck in your favor.

Why Buy OEM

With oil, the safest choice is the one made to meet marine engine expectations, not automotive guesses. This Mercury Marine part is built to meet recognized marine oil requirements and to protect against corrosion, which is a constant threat around water. OEM-grade oil is a practical investment because it supports warranty-minded standards, predictable protection, and long-term engine life.

Aftermarket oils can be fine, but not all are truly marine-focused. My advice to a fellow boater is simple: use oil designed for the water environment, and you’ll worry less and run more.

FAQ Section

Q1: Which Mercury engines or systems does the 10W-40 4-Stroke Marine Engine Oil fit?

It’s intended for four-stroke marine outboard, sterndrive, and inboard engines that specify 10W-40 marine oil in the owner’s manual.

Q2: What makes this part different from aftermarket alternatives?

It’s a Mercury Marine part formulated for marine corrosion protection and high-revolution per minute operation, meeting FC-W standards.

Q3: How do I know if this is the correct replacement for my setup?

Check your owner’s manual for the recommended viscosity and marine oil specification, then match the part number to 8M0148477.

Q4: Can this be used in both saltwater and freshwater applications?

Yes. It’s designed for marine environments in general, including saltwater use where corrosion protection is especially important.

Q5: Is installation straightforward for most boat owners?

Yes. Most owners can handle an oil change with basic tools and the correct procedure. If you’re unsure, a marine shop can do it quickly.