According to the manufacturer, the recommended oils for Mercury outboards are as follows:
OEM 4-Stroke Mercury Oils:
- Mercury 10W-30 Mineral
- Mercury 10W-30 Synthetic Blend
- Mercury 10W-30 Full Synthetic
- Mercury 25W-40 Mineral
- Mercury 25W-40 Synthetic Blend
- Mercury 25W-50 Synthetic Blend
OEM 2-Stroke Mercury Oils:
- Mercury Premium 2-Stroke Engine Oil
- Mercury Premium Plus 2-Stroke Marine Engine Oil Synthetic Blend
- OptiMax Synthetic Blend
OEM Diesel Mercury Oils:
- 15W-40 Heavy-Duty Diesel Engine Oil
- 5W-30 Full Synthetic Turbocharged Direct Injection Diesel Engine Oil
OEM Mercury Gear Lubes:
- 80W-90 Premium Gear Lube
- SAE 90 High-Performance Gear Lube
- 85W-90 Extreme Performance Gear Lube
If you want to know more about what kind of oil Mercury motors use, you are in the right place.
We at PowerSportsGuide have compiled all you need to know under one roof!
Which Engine Oil Can You Use in a Mercury Outboard?
As one may expect, the manufacturer offers their own OEM marine engine oils for Mercury outboards and inboard or sterndrive engines.
Each of these lubricants is specifically formulated for the harsh marine environment and complies with factory service and warranty requirements.
They provide industry-leading wear and corrosion protection and meet all of the needs of Mercury engines.
What’s more, they include premium-grade synthetic and mineral-based stocks as well as unique marine-grade additives.
Since these additives are not required in standard automotive oils, so using standard automotive oils in Mercury engines is definitely not recommended.
Always make sure to use OEM Mercury engine oils or equivalent marine engine oils!
Mercury Engine Oil Chart
For your convenience, we’ve compiled the OEM Mercury oils and their application into one Mercury engine oil chart:
| 2T/4T | Oil Type | Application |
| 2-Stroke | Mercury Premium 2-Stroke Engine Oil | Formulated to meet the needs of low- to mid-HP two-stroke outboard engines under general marine operating conditions. |
| 2-Stroke | Mercury Premium Plus 2-Stroke Marine Engine Oil Synthetic Blend | Formulated for high-horsepower two-stroke outboards, including direct fuel-injected engines. |
| 2-Stroke | Mercury OptiMax Synthetic Blend | Formulated to meet the needs of Mercury OptiMax and direct fuel-injected (DFI) two-stroke outboard engines. |
| 4-stroke | Mercury 10W-30 Mineral | Good choice for Mercury and other brand four-stroke outboard engines. It contains advanced corrosion inhibitors and is FC-W and FC-W Catalyst Compatible. |
| 4-stroke | Mercury 10W-30 Synthetic Blend | It’s FC-W and FC-W Catalyst Compatible and recommended for all brands of four-stroke outboards. |
| 4-stroke | Mercury 10W-30 Full Synthetic | It provides the best wear and corrosion prevention for any engine, especially those operating at maximum output and high temperatures for extended periods of time. |
| 4-stroke | Mercury 25W-40 Mineral | It’s FC-W and FC-W Catalyst Compatible and exceeds all marine industry oil requirements to help maintain peak engine performance and reliability. |
| 4-stroke | Mercury 25W-40 Synthetic Blend | Meets the stringent requirements of high-performance Mercury outboard models and other brand engines. |
| 4-stroke | Mercury 25W-50 Synthetic Blend | It’s recommended for use in all Mercury Racing FormulaRace and Verado® four-stroke outboards as well as non-catalyzed high-horsepower four-stroke marine engines. |
| Diesel | Mercury 15W-40 Heavy-Duty Diesel Engine Oil | Formulated for all marine diesel engines, including Mercury, MerCruiser, and D-Tronic. |
| Diesel | Mercury 5W-30 Full Synthetic Turbocharged Direct Injection Diesel Engine Oil | It resists thermal breakdown and oxidation under extreme conditions to optimize Turbocharged Direct Injection (TDI) diesel engine performance in marine applications. |
(Source)
Which Gear Case Oil Can You Use in a Mercury Outboard?
The recommended gear case lubes for Mercury outboards are as follows:
- Mercury 80W-90 Premium Gear Lube: Recommended for gearcases for Mercury outboards below 75 HP.
- Mercury SAE 90 High-Performance Gear Lube: Formulated to extend gear life in high-speed and high-horsepower sterndrive and outboard gearcase applications.
- Mercury 85W-90 Extreme Performance Gear Lube: Recommended for use in racing, high-performance, and extreme-duty gearcase applications.
OEM Mercury gear case oil is specifically designed for Mercury, Mariner, and Force outboards.
They are formulated to provide excellent corrosion protection and lubrication to lower unit gears.
Also, they feature special additives to protect the gears from excessive wear and metal-to-metal contact.
Takeaways
Mercury outboard engine oils are specifically formulated for harsh marine environments.
High-quality 4-stroke OEM Mercury engine lubricants come in 10W-30, 25W-40, and 25W-50 grades and in mineral, synthetic blend, and full-synthetic formulas.
For 2-stroke outboards, the manufacturer offers its OEM Premium 2-Stroke Engine Oil, Premium Plus 2-Stroke Synthetic Blend Enigne Oil, and OptiMax Synthetic Blend Enigne Oil.
As the name suggests, the latter is recommended for the OptiMax outboard family.
You must never use standard automotive oil in your Mercury outboard since automotive and marine engine oils are very different.
As far as gear lubes go, Mercury markets its OEM 80W-90 Premium Gear Lube for outboards up to 75 HP For high-speed and high-horsepower sterndrive and outboard gearcase applications Mercury offers their SAE 90 High-Performance Gear Lube.
For racing purposes and extreme use, the recommended Mercury gear case lubricant is OEM 85W-90 Extreme Performance Gear Lube.
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