HP = high performance. Advanced formulation delivers increased lubricity to fight piston and cylinder wear, even during lean-mix operation. Potent detergents help prevent piston-ring and exhaust-port deposits despite high-stress, all-day operation. Low-smoke, low-odor formulation also provides low aquatic toxicity.
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Product data sheets
View, download, or save a copy of the Product Data Sheet or Safety Data Sheet for AMSOIL HP Marine® 100% Synthetic 2-Stroke Oil.
AMSOIL HP Marine 100% Synthetic 2-Stroke Oil is a fully synthetic, NMMA TC-W3 lubricant engineered for modern outboards, including direct fuel injection (DFI), EFI, and carbureted two-stroke designs. The formulation is built for boaters running Evinrude, Johnson, Evinrude FICHT, Evinrude E-TEC, Mercury EFI and Optimax, Yamaha (including HPDI), Nissan, Tohatsu TLDI, Suzuki, Mariner, and Force outboards that call for a TC-W3 oil at the factory-lean setting or in 50:1 premix service. The formula controls friction, heat, and wear while delivering low-smoke, low-odor combustion and low aquatic toxicity for sensitive marine environments.
Wear protection at lean-mix and DFI operating ratios
Direct fuel injection improves combustion efficiency and reduces emissions, but the leaner gas-to-oil ratios in modern outboards leave less oil to lubricate hotter, harder-working motors. The exclusive synthetic formulation in HP Marine increases lubricity and film strength to fight piston ring sticking and piston scuffing during normal and lean-mix operation. In a field study with a 40-hp Evinrude E-TEC outboard set to its factory-lean setting and run for a full season of rental service in northern Minnesota, HP Marine prevented piston ring sticking and piston scuffing across the test, supporting maximum power and long engine life.
MAXDOSE detergent control for ring jacking and exhaust port deposits
HP Marine is formulated with the MAXDOSE additive system for super-clean operation in DFI, EFI, and carbureted two-stroke marine motors. In field testing the formula prevented ring sticking and ring jacking, the carbon buildup behind the ring that forces the ring outward in modern DFI outboards. The same testing virtually eliminated exhaust port deposits, the kind of buildup that erodes power, throttle response, and fuel economy across a season of hard use.
Low smoke, low odor, and low aquatic toxicity
HP Marine passes the JASO M 342-92 Smoke Test at the FD level for low visible smoke at idle, in no-wake zones, while trolling, and through extended cruise. Aquatic toxicity testing follows OECD Guideline 203 (Fish Acute Toxicity) and OECD Guideline 202 (Daphnia Acute Immobilization), each producing a 100 percent survival rate in laboratory testing. The combination of low smoke, low odor, and low aquatic toxicity makes HP Marine well suited for boaters running on inland lakes and saltwater coastlines where engine emissions and water quality are a concern.
Rust protection and TC-W3 lubricity for layup and intermittent service
Marine two-strokes that sit between weekend trips face condensation, salt spray, and stand-by corrosion that can attack cylinder walls and bearings. HP Marine passes the NMMA TC-W3 Rust Test for protection during storage and intermittent service, and it passes the TC-W3 Lubricity Test (ASTM D4863) covering anti-scuff performance under load. The formula also delivers a viscosity index of 160 (ASTM D2270) and a pour point of -55 C / -67 F (ASTM D97), keeping oil flowing at first start in cold spring water and through early-season fog runs.
Recommended applications and service
HP Marine is built for two-stroke marine applications that specify NMMA TC-W3 service. The oil performs as either an oil-injection fluid or a 50:1 premix, mixed at 2.6 ounces per U.S. gallon of gasoline. The certified application list covers Evinrude and Johnson, Evinrude FICHT and E-TEC, Mercury EFI and Optimax, Yamaha (including HPDI), Nissan, Tohatsu TLDI, Suzuki, Mariner, and Force outboards, plus marine personal watercraft that specify a TC-W3 fluid.
Oil-injection service: load HP Marine into the integrated oil tank for motors that meter oil through a pump at the factory-lean setting.
Premix service: blend at 50:1, equal to 2.6 ounces per U.S. gallon of gasoline, for outboards designed to run on a pre-mixed gas-and-oil charge.
Mixing: HP Marine is compatible with mineral and synthetic TC-W3-type two-stroke oils, but mixing two-stroke oils should be minimized to keep the MAXDOSE additive system performing as designed.
Outside the United States and Canada, follow the outboard manufacturer's recommended fuel-to-oil ratio and oil-injection setting.
HP Marine ships ready for the tank, and aftermarket two-stroke oil additives are not recommended for use with the formula. Service the outboard's fuel filter, water-separating filter, and lower-unit gear lube on the schedule published by the outboard manufacturer. Confirm the correct fuel-to-oil ratio and TC-W3 application for the motor with the AMSOIL Vehicle Lookup Guide before ordering.
Typical technical properties
Property
Value
Kinematic Viscosity at 100 C, cSt (ASTM D445)
7.3
Kinematic Viscosity at 40 C, cSt (ASTM D445)
37.3
Viscosity Index (ASTM D2270)
160
Brookfield Viscosity at -40 C, cP (ASTM D2983)
13,696
Pour Point, C (F) (ASTM D97)
-55 (-67)
Flash Point, C (F) (ASTM D92)
104 (219)
Fire Point, C (F) (ASTM D92)
104 (219)
NMMA TC-W3 Rust Test
Pass
JASO M 342-92 Smoke Test (FD)
Pass
TC-W3 Lubricity Test (ASTM D4863)
Pass
OECD Guideline 203 Fish Acute Toxicity Test
100 percent survival
OECD Guideline 202 Daphnia Acute Immobilization Test
100 percent survival
Order AMSOIL HP Marine 2-Stroke Oil
HP Marine is available in a quart bottle (HPMQT-EA), case of 12 quarts (HPMQT-CA), gallon jug (HPM1G-EA), 16 gallon keg (HPM16-EA), and 55 gallon drum (HPM55-EA). HP Marine is Warranty Secure and is backed by the AMSOIL Limited Warranty (G1363), so factory engine warranties remain intact when the oil is used as directed. Match the right grade for the outboard with the AMSOIL Vehicle Lookup Guide, review TC-W3 selection, oil-injection use, and 50:1 premix guidance in the Marine 2-Stroke Oil Guide, then order AMSOIL HP Marine 100% Synthetic 2-Stroke Oil.
Use in both boats , Charger ski/speed with Yamaha VMax 200 Glassport Bass with Merc 150 Both run hard, clean
By Denis from Wasaga Beach on July 07, 2026.
Would recommend this to a friend.
Great Oil but......
This is the best oil for an old two stroke cleanest plugs I’ve ever seen but the discount coupons expire too soon and the gimmicky free gifts are a joke
By Roy from michigan on September 26, 2025.
Would recommend this to a friend.
Oil is great , price and shiping is super
This is about half the price of the mercury optimax DFI oil, and Amsoil is always available, which can't be said for the merc product. I've placed 2 orders for this oil and both times, it arrived on my doorstep within 2 days. Can't be happier.
By Dave from North Bay, Ont on September 19, 2025.
NMMA TC-W3 is the marine industry's certification for water-cooled two-stroke outboard oils. The standard covers lubricity, rust protection, fluidity, smoke, deposit control, and compatibility for outboards that mix oil with the fuel charge. HP Marine carries the NMMA TC-W3 license and passes the associated rust and lubricity tests, so the oil is approved for service in outboards that call for a TC-W3 fluid.
Can HP Marine be used in a Mercury Optimax or Yamaha HPDI outboard?
Yes. HP Marine is built for direct fuel injection and EFI two-stroke outboards that specify a TC-W3 oil, including Mercury EFI and Optimax and Yamaha (including HPDI). The MAXDOSE additive system targets ring jacking and exhaust port deposits common in DFI outboards run at the factory-lean setting.
What ratio should be used for premix?
Mix HP Marine at 50:1, which is 2.6 ounces per U.S. gallon of gasoline. The same oil works as oil-injection fluid in motors with an integrated oil tank, so a single product covers both portable premix tanks and oil-injected outboards.
Will HP Marine work in older Evinrude, Johnson, or Force outboards?
Yes. The TC-W3 specification covers older oil-injected and premix two-strokes from Evinrude, Johnson, Evinrude FICHT, Evinrude E-TEC, Nissan, Tohatsu TLDI, Suzuki, Mariner, and Force. Confirm the recommended fuel-to-oil ratio in the outboard manufacturer's service guidance before refilling the reservoir, and verify application match with the AMSOIL Vehicle Lookup Guide.
Is HP Marine safe for saltwater outboards?
Yes. HP Marine passes the NMMA TC-W3 Rust Test for protection during storage and intermittent saltwater service, and the formula is engineered for low aquatic toxicity per OECD Guideline 203 (Fish) and OECD Guideline 202 (Daphnia), each at 100 percent survival in laboratory testing. Continue to follow the outboard manufacturer's saltwater flush procedure between trips.
Can HP Marine be mixed with another TC-W3 oil?
HP Marine is compatible with mineral and synthetic TC-W3-type two-stroke oils, but mixing should be minimized so the MAXDOSE additive system can perform as designed. When changing brands, run the existing oil tank low before refilling with HP Marine.
Does using AMSOIL HP Marine void the outboard warranty?
No. HP Marine is Warranty Secure and is backed by the AMSOIL Limited Warranty (G1363). Using AMSOIL synthetic lubricants does not void a new vehicle or equipment manufacturer warranty when the product is used as directed.
