AMSOIL first in synthetics
Tracey Dean
Austin & Kyle, TX
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AMSOIL Synthetic Marine Oil

We have a list of products specifically selected for boats and personal watercraft applications. Select from synthetic 2-stroke and 4-stroke marine oils, marine gear lubes and greases, filtration products, fuel additives and much more. 

AMSOIL Diesel Motor Oil

Why you should use synthetic oil in your boat engines

Regardless of the application you are looking for, whether it is for a high performance ski-boat, bass boat, offshore race boat, or for an auxiliary engine on a sailboat, AMSOIL has a designed product that is engineered specifically for your application. AMSOIL has two high performance synthetic NMMA-approved 4-cycle Marine Engine Oils and several synthetic 2-cycle oils designed for specific applications, including jetskis, EFI and DFI outboard motors, and racing applications.

Most anglers work full-time and have precious little time for fishing. To maximize their time on the water, they need lubricants that protect their motors from wear despite challenging operating conditions.

Much like automotive engines, marine motors are becoming more advanced and tougher on oil. Four-stroke motors are becoming lighter and produce more low-end torque than before. They’ve largely closed the performance gap on two-stroke motors. In fact, sales of four-stroke motors are on the rise, while two-stroke sales have declined.

Demanding Operating Conditions

Marine motors are characterized by high-rpm operation that can shear the molecular structure of oil and reduce its ability to protect against wear. On average, a marine motor propelling a boat 30 mph operates at 5,000 rpm,

while an automotive engine at 60 mph operates around 2,000 rpm. The added heat and stress invite wear and deposits. Heavy deposits can cause piston rings to stick. Stuck rings lead to compression loss, which reduces power. Stuck rings can also lead to catastrophic piston scuffing.

The marine operating environment creates additional challenges for oil. Marine motors are constantly exposed to humid air. The moisture the motor ingests increases the likelihood of corrosion compared to automotive engines. Water-cooled marine motors also run at lower temperatures than air-cooled engines, so moisture in the oil doesn’t evaporate as readily. Plus, when the motor is shut down for the day, moist air continues to enter the engine as it cools, increasing the risk for corrosion, especially if the oil doesn’t contain anti-corrosion inhibitors.

Marine-Specific Four-Stroke Formulations

AMSOIL 10W-30 and 10W-40 Synthetic Marine Engine Oil and new AMSOIL 25W-40 Synthetic-Blend Marine Engine Oil are shear-stable formulations that deliver maximum wear protection in four-stroke marine applications. They are formulated with advanced additives to guard against corrosion common to marine environments.

Marine-Specific Two-Stroke Formulations

AMSOIL synthetic two-stoke marine oils provide the same great benefits as always, including outstanding wear protection and low smoke. AMSOIL HP Marine® Synthetic 2-Stroke Oil is excellent in modern direct-fuel-injected (DFI) motors that generate increased heat and friction compared to their predecessors. It provides increased lubricity for reduced wear during normal and lean-mix operation. In field testing, HP Marine completely prevented piston skirt and cylinder bore scuffing (see for details.)

AMSOIL Synthetic 2-Stroke Injector Oil protects against wear and piston scuffing while providing the added benefit of year-round use as a snowmobile oil.

For pre-mix applications, AMSOIL Outboard 100:1 Pre-Mix Synthetic 2-Stroke Oil contains a heavy dose of low-temperature dispersant additives that excel at reducing varnish, carbon and deposit formation in water-cooled motors. Its low-smoke, low-odor, low-toxicity properties produce fewer emissions at 100:1 mix ratios than oils mixed at 50:1, benefitting operators and the environment.

AMSOIL Synthetic Marine Gear Lube protects lower units from wear, even when contaminated with up to 10 percent water. 

Why Synthetic Blend?

AMSOIL 25W-40 Synthetic-Blend Marine Engine Oil is formulated specifically for Mercury* motors that encourage the use of synthetic-blend oil.

Fishing Boats
The anticipation and adrenaline of catching your limit is tough to beat. AMSOIL synthetic lubricants deliver the engine response and precision performance you need to stay on the fish all day.
Pleasure Boats
Protect your boat for uninterrupted fun on the water with superior protection against engine wear, rust and corrosion.
Diesel Boats
The open water is where you feel free, and where the excellent engine performance and premium protection provided by AMSOIL synthetic lubricants are essential.
Personal Watercraft
Fuel high-speed fun on the open water by keeping your personal watercraft running clean and smooth with AMSOIL synthetic lubricants.
Pontoon Boats
Cruising on the water with family and friends is always enjoyable, especially with the peace of mind that only AMSOIL synthetic lubricants can deliver
HP Marine™: High Performance, Low Aquatic Toxicity

HP Marine Synthetic 2-Stroke OIl (HPM) can help you get hours of trouble-free enjoyment out of your two-stroke outboard and personal watercraft.

Maintaining today’s two-stroke marine motors can intimidate even experienced enthusiasts. Like passenger cars/light trucks, many two-stroke outboard motors come equipped with computerized controls and sophisticated fuel-injection systems designed to deliver the extra power enthusiasts want while providing the reduced exhaust emissions the government mandates. The leaner gas-to-oil ratios these engines use mean less oil is available to lubricate and protect a hotter, more powerful engine, inviting deposits and wear that threaten engine performance and life. Using HP Marine Synthetic 2-Stroke Oil is one of the easiest steps anglers, boaters and personal watercraft owners can take to ensure their equipment provides hours of trouble-free enjoyment. As an injection oil or 50:1 pre-mix, HP Marine is specifically formulated to control harmful deposits and wear in today’s advanced two-stroke marine applications and is recommended for all two-stroke outboards.

Prevents Ring Sticking & Piston Scuffing

To prove it, AMSOIL put HP Marine to the test in one of the most demanding two-stroke marine engines on the market – the 250-hp Evinrude® E-TEC®. The E-TEC is unique in that it offers a lean-mix setting that allows the engine to use less oil. Over 500 hours of real-world operation powering a marine rescue vessel, almost all at the engine’s lean-mix setting, HP Marine completely prevented piston ring sticking and piston scuffing. The lubricant also limited deposits throughout the engine and provided excellent wear protection for the cylinders and bearings. HP Marine is as advanced as the engines it protects, helping enthusiasts get the most out of their equipment. Complete test results are available in the Marine E-TEC® Field Study (G2968). HP Marine also boasts proven low aquatic toxicity. AMSOIL set the standard as the first lubricant manufacturer to incorporate testing developed by the Organisation for Economic Cooperation and Development (OECD); it reveals a 100 percent survival rate of Daphnia Magna neonates (water fleas) and fathead minnows exposed to increasing concentrations of HP Marine mixed in water. HP Marine is the perfect lubricant for marinas and those who value performance and environmental sustainability.