Best 2 Stroke Marine Oil

Amsoil 2 cycle snowmobile and outboard oils



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Best 2 Stroke Oil Marine Outboard

2 cycle Injection Oil or 50:1 pre-mix

HP Injector Synthetic 2-Cycle Oil (HPI)Amsoil hp Marine Injector Synthetic 2-stroke Oil (HPI)
Best 2 stroke marine oil, Excellent for injection in all outboard motors with a performance emphasis on modern direct fuel injected (DFI) technology. Also recommended for personal watercraft, jet boats, motorcycles, snowmobiles and ATVs. Injection use or 50:1 premix.
See how to get Amsoil HPInjection oil at wholesale

Package sizes include:

1-Quart Bottle
1-Quart Bottles (case of 12)
1-Gallon Bottle
1-Gallon Bottles (case of 4)
16-Gallon Keg


  • Superior performance in DFI outboard motors
  • Reduces piston and combustion chamber deposits
  • Protects against "ring jacking" common to DFI outboards
  • Low smoke, low odor product
  • Contains up to 30 percent more additives for "super clean" operation
  • Reduces wear for long engine life
  • Protects against rust
  • Multi-functional and recommended for use in many two-cycle motors
  • Low aquatic toxicity
  • Recommended for use as injection oil or at a 50:1 pre-mix

hp Injector is a precise synthetic formulation that exceeds the lubrication demands of modern two-cycle motors. Today’s two-cycle outboard motors operate at higher temperatures and at leaner oil and fuel ratios than older motors. This difficult operating environment requires proper lubrication technology to keep motors running long and strong. hp Injector is a premium lubricant engineered with AMSOIL synthetic base oils and MAXDOSE advanced additives. It contains up to 30 percent more additives than other TC-W3 two-cycle oils for “super clean” operation. And because AMSOIL synthetic oils are more durable, they are perfect for lean mixture operations. In addition, this AMSOIL exclusive product produces low smoke and odor and has low aquatic toxicity properties, making it ideal for boats.

hp Injector improves engine life. It helps prevent deposits that cause ring sticking and ring jacking (carbon build-up behind the ring, forcing it outward), a phenomenon that occurs in modern DFI outboard motors. hp Injector reduces wear. It has excellent lubricity properties and provides a good lubricating oil film, protecting pistons and bearings. hp Injector protects against rust, an important feature where motors are subjected to water. hp Injector provides superior performance in direct fuel injected (DFI), semi-direct fuel injected (SDI), electronic fuel injected (EFI) and carbureted outboard motors, as well as other recreational equipment.

Applications (2-Cycle Recommendations Chart)
hp Injector is recommended for use in all two-cycle outboard motors including, but not limited to, Mercury® EFI & Optimax®, Johnson® and Evinrude® FICHT® and E-TEC™, Yamaha® HPDI, Nissan® and Tohatsu® TLDI®, Suzuki®, Mariner® and Force®. Also recommended for use in all two-cycle personal watercraft and jet boats, as well as snowmobiles, motorcycles and ATVs.

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Use as injection oil or as 50:1 pre-mix (2.6 oz. per U.S. gallon of gas) where NMMA TC-W3 or API TC oils are specified. Compatible with mineral and synthetic TC-W3-type two-cycle oils, however, mixing two-cycle oils should be minimized.

hp Injector Synthetic 2-Cycle Oil

Kinematic Viscosity @ 100°C, cSt (ASTM D-445)


Kinematic Viscosity @ 40°C, cSt (ASTM D-445)

Viscosity Index (ASTM D-2270)

Pour Point °C (°F) (ASTM D-97)

-46 (-51)

Flash Point °C (°F) (ASTM D-92)

86 (187)
Fire Point °C (°F) (ASTM D-92)
86 (187)
DANGER: harmful or fatal if swallowed. Contains synthetic lubricant and petroleum distillates. If swallowed do not induce vomiting. Contact a physician immediately. Keep away from fire, heat and open flame. Use with adequate ventilation. Avoid frequent or prolonged skin contact. Flush eyes with water for 15 minutes in case of contact. KEEP OUT OF REACH OF CHILDREN.

Q: A boat owner asks, Can I use Amsoil HP in an Evinrude e-tech outboard? A: Yes you can i replied. Read our Marine E-TEC Field Study below. Our Synthetic 2-Stroke marine Oil provides excellent protection in Evinrude engines programmed to the lean-mix setting.

Evinrude® E-TEC™ marine engines are unique in that they offer an alternative, lean-mix setting that allows the engine to use less oil. Whether programmed to operate at the standard mix ratio or reprogrammed to the lean-mix setting, these engines use sophisticated electronic equipment to monitor conditions, including rpm and throttle position, to determine the appropriate gas-to-oil mixture. To use the lean-mix setting, however, customers must have their engines reprogrammed by an Evinrude dealer and agree to use Evinrude XD100™ oil exclusively, often at a higher cost compared to other oils. Bombardier Recreational Products (BRP®), the manufacturer of Evinrude engines, has not established a performance specification against which to qualify other oils.

Determine through real-world field validation if AMSOIL HP MarineTM Synthetic 2-Stroke Oil meets the
increased performance needs of reprogrammed Evinrude E-TEC engines operating on the lean-mix setting. Further determine if consumers can safely use HP Marine Synthetic 2-Stroke Oil in E-TEC applications in place of Evinrude XD100 2-Cycle Oil.

Package sizes include:

  • Quart Bottle
  • 1-Gallon Bottle
  • 16-Gallon Keg
  • 55-Gallon Drum
  • 275-Gallon Tote

How to order Amsoil HP marine 2 stroke outboard oil

In conducting this field study, AMSOIL partnered with SEA-TOW®, a marine rescue organization specializing in non-emergency calls for assistance. Based in Naples, Fla., SEA-TOW typically tows large marine vessels, including yachts and sport cruisers. The engines that power their towing vessels routinely encounter heavyduty, high-stress operation and provide the ideal environment for testing motor oils. Both Evinrude 250 hp E-TEC engines used in the study were initially operated on the standard oil injection setting for 28 hours. An Evinrude dealer then reprogrammed both engines to operate on the lean-mix setting for the duration of the study. The starboard engine’s oil reservoir was filled with AMSOIL HP Marine Synthetic 2-Stroke Oil, the portside engine’s oil reservoir with Evinrude XD100 2-Cycle Oil. The validation period lasted a total of 534 hours; approximately 240 hours were spent under severe-service conditions when the SEA-TOW boat towed marine vessels. The engines were closely monitored for the duration, and upon completion, both were disassembled and rated by a calibrated ASTM rater who evaluated each engine based on NMMA TC-W3 criteria for two-cycle marine engines. Merit ratings for each set of components (e.g. piston skirts, piston rings, etc.) were determined using the appropriate techniques and rating scales as defined in the Coordinating Research Council, Inc. Deposit Rating Manual No. 20. The evaluation included an examination of the condition of all engine parts. Some components received a merit rating based on a 1-10 scale, with 10 representing a component free of defects and 0 representing catastrophic distress. Others received merit ratings indicating the percentage of an area with defects (e.g. the percentage piston skirt area containing scuffing). The average merit rating of each group of components is shown in this study.

Piston Skirts

  Portside using Amsoil HP____________________Portside side using Evinrude XD100

Portside of engine using Amsoil HPPortside Using Evinrude XD 100


  Starboard Side Using Amsoil HP_________________ Starboard using Evinrude XD100

Starboard side Using Amsoil HPStarboard side using Evinrude XD100

AMSOIL HP Marine Synthetic 2-Stroke Oil

Piston Varnish 8.52
Piston Skirt Condition (scratching) 1.42%
Piston Scuffing 0.00%

Evinrude XD100 2-Cycle Oil

Piston Varnish 8.57
Piston Skirt Condition (scratching) 1.25%
Piston Scuffing 0.00% 

The pistons in both engines received nearly identical high merit ratings for varnish, indicating both oils
excelled at inhibiting varnish formation. Scratching refers to the alteration of the skirt surface in the form of sharp linear depressions from lapping of mating surfaces by fine particles suspended in the lubricant, fuel, air or imbedded in a surface, while scuffing appears as a matte finish. The presence of scuffing is commonly lubricant-related. In both engines, scratching was present at trace to very light levels, represented by the low percentage ratings. Both oils completely prevented piston skirt scuffing, earning perfect ratings of 0.00 percent scuffing.


Piston Rings & Lands

AMSOIL HP MarinePiston rings Evinrude XD100 2-Cycle Oil

AMSOIL HP Marine Synthetic 2-Stroke Oil

Top Ring Sticking & Deposits 10.00
Second Ring Sticking & Deposits 10.00
Crown Land Deposits 3.98
Second Land Deposits 5.91

is made between
thrust side and
anti-thrust side
for ring and land

Evinrude XD100 2-Cycle Oil

Top Ring Sticking & Deposits 10.00
Second Ring Sticking & Deposits 10.00
Crown Land Deposits 2.99
Second Land Deposits 6.82

 Deposits on the piston rings can cause ring sticking and consequent power loss. The top rings and second rings in both engines earned perfect merit ratings of 10.00, demonstrating no piston ring deposits. Merit ratings for crown land and second land deposits were similar for both engines.

Cylinder Heads

Cylynder heads using Amsoil HP   Cylynder heads using Evinrude XD100

AMSOIL HP Marine Synthetic 2-Stroke Oil

Cylinder Head Deposits 8.76

Evinrude XD100 2-Cycle Oil

Cylinder Head Deposits 8.14

Excessive cylinder head deposits are undesirable and can negatively affect engine performance. Both oils earned high ratings for deposit control, indicating good cleanliness properties.

Piston Crowns & undercrowns

AMSOIL HP Marine Synthetic 2-Stroke OilEvinrude XD100 2-Cycle Oil

 AMSOIL HP Marine Synthetic 2-Stroke Oil

Piston Crown Deposits 7.02
Piston Undercrown Deposits 2.18

 Evinrude XD100 2-Cycle Oil

Piston Crown Deposits 6.31
Piston Undercrown Deposits 2.66

While undercrown deposits do not impede performance, heavy piston crown deposits can cause preignition and consequent poor performance. Two-cycle oils must resist heavy deposit formation on the piston crown caused by the high temperatures inside the combustion chamber. HP Marine demonstrated strong performance in the area of piston crown deposits.

Connecting Rod Assemblies

connecting rod assemblys using Amsoil HP  connecting rod assemblys using Evinrude XD100

 AMSOIL HP Marine Synthetic 2-Stroke Oil

Wristpin: Condition/Deposits 6.82
Rod Bearing, Crankpins: Condition/Deposits 9.90
Rod Bearing, Wristpins: Condition/Deposits 8.38

 Evinrude XD100 2-Cycle Oil

Wristpin: Condition/Deposits 8.38
Rod Bearing, Crankpins: Condition/Deposits 9.88
Rod Bearing, Wristpins: Condition/Deposits 7.62

Connecting rod assembly components are exposed to elevated temperatures and pressures that can rupture the oil film, leading to metal-to-metal contact and wear. The wristpins, crankpin rod bearings and wristpin rod bearings in both engines demonstrated trace to light levels of wear and were found to be in “good” condition according to the calibrated ASTM rater. Deposits on all components were limited to levels not adversely affecting performance.

Connecting Rods

Connecting rods using Amsoil hp   connecting rods using Evinrude XD 100

 AMSOIL HP Marine Synthetic 2-Stroke Oil

Wristpin Bearing Race: Condition/Deposits 7.90
Crankpin Bearing Race: Condition/Deposits 9.67

 Evinrude XD100 2-Cycle Oil

Wristpin Bearing Race: Condition/Deposits 7.98
Crankpin Bearing Race: Condition/Deposits 9.73

The wristpin and crankpin bearing races undergo constant rotational stress, inviting wear. Bearing races in both engines demonstrated trace to light levels of wear and were found to be in “good” condition according to the calibrated ASTM rater. Deposits were limited to low levels in both engines.


  Cylinders Using Amsoil         Cylinders using Evinrude

 AMSOIL HP Marine Synthetic 2-Stroke Oil

Exhaust Port Blocking 1.08%
Exhaust Port Deposits 9.89
Cylinder Bore Scuffing 0.00%

 Evinrude XD100 2-Cycle Oil

Exhaust Port Blocking 1.17%
Exhaust Port Deposits 9.88
Cylinder Bore Scuffing 0.00%

Carbon deposit buildup in the exhaust ports restricts air flow and can cause reduced power and poor overall performance. Both engines displayed virtually no exhaust port blocking, represented by the low percentages. Deposits were likewise minimal, with ratings near perfect 10s. In the area of cylinder bore scuffing, both oils limited metal-to-metal contact and achieved perfect scores of 0.00 percent. The cross-hatch pattern remains visible on the cylinder walls of both engines.


Crankshaft using Amsoil

AMSOIL HP Marine Synthetic 2-Stroke Oil

Crankshaft Crankpin: Condition/Deposits 9.85
Crankshaft Main Journal: Condition/Deposits 9.78


Crankshaft using Evinrude

Evinrude XD100 2-Cycle Oil

Crankshaft Crankpin: Condition/Deposits 9.85
Crankshaft Main Journal: Condition/Deposits 9.78

The crankpins and main bearing journals experience elevated pressures during operation and represent
common suffering points. In both engines, the crankpins and main bearing journals demonstrated trace to light wear and were found to be in “good” condition according to the calibrated ASTM rater. Ratings for deposits were nearly perfect for both engines.

Main Bearings

Main bearings using Amsoil   Main bearings using Evinrude

 AMSOIL HP Marine Synthetic 2-Stroke Oil
Crankshaft Main Bearings: Condition/Deposits 9.95
 Evinrude XD100 2-Cycle Oil
Crankshaft Main Bearings: Condition/Deposits 9.89

 The main bearings experience intense pressure and represent a common area where metal-to-metal contact can occur. Both oils limited wear to trace to light levels and the bearings were found to be in “good” condition according to the calibrated ASTM rater. Both oils nearly eliminated deposits as well.


As demonstrated in real-world, severe-service testing, AMSOIL HP MarineTM Synthetic 2-Stroke Oil meets the stringent performance needs of Evinrude® E-TECTM marine engines programmed for reduced oil consumption. Operated simultaneously with an engine lubricated with Evinrude XD100, an identical engine lubricated with HP Marine demonstrated strong performance and excelled in critical-component lubrication. The cylinder bores, for example, demonstrated 0.00 percent scuffing, while the main bearings demonstrated only trace to light wear. The engine also displayed no ring deposits, earning perfect merit ratings. Finally, HP Marine effectively limited deposits throughout the engine and met the increased performance demands required by the lean-mix setting. Results prove the effectiveness of AMSOIL HP Marine Synthetic 2-Stroke Oil in Evinrude E-TEC applications.
AMSOIL fully supports the use of HP Marine as a replacement for Evinrude XD100 in Evinrude
E-TEC engines, and warrants its use according to the AMSOIL Limited Liability Warranty (G1363).

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