Mercury – 25W-40 4-Stroke Marine Engine Oil, 1 Quart (6-Pack) | FourStroke Lubrication Series | Marine Engine Oil | 8M0078627

Overview

Marine engines live a tougher life than most people realize. One day it’s a long, hot run across open water, the next it’s slow idling in a no-wake zone with humid air hanging around the motor. Heat, load, moisture—it all adds up. That’s why using the right oil matters more on a boat than just about anywhere else.

This Mercury 25W-40 4-Stroke Marine Engine Oil comes as a six-quart pack, which makes it a practical choice for full oil changes or keeping extras on hand. It’s the same dependable quart oil Mercury owners rely on, just packaged so you’re ready when service time rolls around. No guessing, no mixing brands—just pour, run, and get back to enjoying the day.

Key Features

• Six-pack of 1-quart bottles of Mercury 25W-40 4-Stroke Marine Engine Oil

• Formulated specifically for marine engines operating in harsh, corrosive environments

• 25W-40 viscosity rating for strong protection across a wide temperature range

• Designed to resist wear and corrosion under sustained load and high RPM use

• Maintains viscosity and film strength during long runs and heavy throttle

• Certified to FC-W and catalyst-compatible FC-W standards

• Recommended for Mercury, MerCruiser, and other four-stroke marine engines requiring 25W-40

• Produced to Mercury Marine OEM specifications

• Mercury Marine part number 8M0078627

Engine & Boat Compatibility

• Four-stroke outboard engines that specify 25W-40 marine oil

• Four-stroke sterndrive engines requiring 25W-40 marine oil

• Four-stroke inboard engines calling for 25W-40 viscosity

• Commonly used on bass boats, pontoons, center consoles, cruisers, and runabouts

• Always confirm oil grade and capacity in your owner’s manual

Performance & Practical Benefits

A good oil change does more than protect parts—it changes how the engine feels. With the right 25W-40 marine oil, engines tend to run smoother once warm, stay more stable at cruise, and feel less stressed when you lean into the throttle. This oil is built to hold its viscosity when the engine is working hard, which matters during long runs or heavy use days.

Corrosion protection is just as important. Boats sit. They cool down. Moisture hangs around longer than it ever would in a car. This marine-specific additive package helps protect internal components both on the water and during downtime, which is especially valuable for weekend and seasonal boaters.

The six-quart pack also makes maintenance easier. It’s ideal for full oil changes on many four-stroke engines, and any extra bottles are easy to store for top-offs later. No scrambling for another quart mid-service—everything you need is already there.

Why Buy OEM

Oil is one of those areas where keeping it simple pays off. Using genuine Mercury Marine oil means you’re running a formula designed specifically for marine engines, not an automotive oil trying to do double duty. It meets recognized marine standards, supports manufacturer recommendations, and is engineered to protect engines the way Mercury intended.

Aftermarket oils can work, but not all are truly marine-certified or focused on corrosion control. If you want consistent performance, easy maintenance, and fewer questions over the season, OEM oil is the straightforward choice.

FAQ

Q1: What engines is this 25W-40 marine oil designed for?
It’s intended for four-stroke outboard, sterndrive, and inboard engines that specify 25W-40 marine oil in the owner’s manual.

Q2: Is this listing for a single bottle or multiple bottles?
This listing includes a six-pack of 1-quart bottles.

Q3: What makes this oil different from automotive 25W-40 oils?
It’s formulated for marine use, with added corrosion protection and certification to FC-W marine standards.

Q4: Can this oil be used in both saltwater and freshwater applications?
Yes. It’s designed for marine environments, including saltwater where corrosion resistance is critical.

Q5: Is this suitable for DIY oil changes?
Yes. Most boat owners can perform an oil change with basic tools and the proper procedure outlined in the owner’s manual.