High RPM 4-stroke marine engine oil

August 26, 2021

High RPM marine engine oil

Jetski Image by Herbert Aust from Pixabay… Thank you Herbert!

High RPM marine engine oil

Marine engine oil is constantly under load. AMSOIL manufactures its high rpm marine engine oil for 4-cycle water cooled (*NMMA FC-W) engines. Our customers find better throttle response and overall engine performance.

AMSOIL 4-stroke marine engine oil

The typical marine engine will run about 5000 rpm at 30 mph compared to an automobile engine that runs at about 2000 rpm at 60 mph. Unlike an automobile engine that eases its load with coasting or downhill travel a marine engine rarely coasts. High heat and high rpm can easily break down the oil’s viscosity causing it to become thinner. Thinner oil can no longer separate moving parts from wear and friction. AMSOIL’s extreme film strength resist viscosity shear for longer lasting lubrication of moving parts eliminating metal to metal contact. Engines run quieter and perform their best so you get the most power and performance from you engine all season long. For high-rpm running engines, AMSOIL keeps inboard/ outboard engines and personal watercraft engines running their best.

*AMSOIL 4-stroke oil for marine engines are certified by the National Marine Manufacturers Association (NMMA), meeting the requirements of Four Cycle – Water-cooled (NMMA FC-W) Catalyst Compatible specification, which is backward-compatible with the FC-W specification.


Frequently asked questions

What kind of engines should AMSOIL 25W-40 synthetic-blend marine engine oil be used in?

This engine oil is suitable for use in applications requiring a 25W-40 marine engine oil, such as Mercury* outboard engines and the Mercury Verado*.


Why did AMSOIL create a synthetic-blend oil rather than a full synthetic oil for its 25W-40 synthetic-blend marine engine oil?

This oil is specifically formulated for Mercury 4-stroke engines that use synthetic-blend oil, as Mercury’s owner’s manuals discourage the use of full synthetic oil. Since most Mercury owners prefer to stay within the parameters of the manufacturer’s guidelines, AMSOIL 25W-40 synthetic-blend marine engine oil was created.


I have been using AMSOIL 10W-40 synthetic marine engine oil in my Mercury engine, but will my original equipment manufacturer (OEM) warranty still be valid?

The answer is yes! AMSOIL synthetic lubricants are Warranty Secure®, protecting your OEM warranty. If you like the performance of 10W-40 synthetic marine engine oil, you can keep using it. AMSOIL still guarantees this oil when the OEM calls for a 40-weight marine engine oil.


What is an NMMA-licensed oil?

The National Marine Manufacturers Association (NMMA) certifies certain types of marine engine oils by evaluating whether they meet or exceed the necessary performance and environmental standards for their intended purpose. AMSOIL 10W-30 and 10W-40 synthetic marine engine oil, and AMSOIL 25W-40 synthetic-blend marine engine oil have all been approved by the NMMA.


What separates HP Marine® Synthetic 2-Stroke Oil from Outboard Pre-Mix Synthetic 2-Stroke Oil?

The main distinction between HP Marine® synthetic 2-stroke oil and Outboard Pre-Mix synthetic 2-Stroke oil is that the former is intended for high-performance two-stroke marine engines, protecting them from ring sticking, piston scuffing, and corrosion. It can be used for both injection and pre-mix, while the latter is specifically designed for pre-mix outboards as it enables a lean mix ratio which helps to prevent plug fouling and carbon deposits while extending the engine life.

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