AMSOIL guide
Marine 2-Stroke Oil Guide
AMSOIL builds three synthetic 2-stroke marine oils, all carrying the NMMA TC-W3 certification: HP Marine for direct-injected and high-output outboards, 100:1 Pre-Mix for premix outboards and PWCs, and 2-Stroke Injector Oil for value injector use. Pick HP Marine for current Evinrude E-TEC, Mercury OptiMax, Yamaha HPDI, and Suzuki DI engines. Pick 100:1 Pre-Mix for premix outboards and almost every personal watercraft. Pick Injector Oil for older injector-pump outboards where the maximum-performance margin of HP Marine is not required.
AMSOIL marine 2-stroke oil lineup at a glance
| Product | Best fit | Where to buy |
|---|---|---|
| HP Marine 100% Synthetic (HPM) | Evinrude E-TEC, Mercury OptiMax, Yamaha HPDI, Suzuki DI direct-injected outboards | Buy online |
| 100:1 Pre-Mix Synthetic (ATO) | Premix outboards, PWCs, jet boats, leanest-mix tolerant | Buy online |
| 100% Synthetic 2-Stroke Injector Oil (AIO) | Most 2-stroke injector-pump outboards, value pick | Buy online |
What TC-W3 means and why it matters
TC-W3 is the National Marine Manufacturers Association (NMMA) certification for water-cooled 2-stroke outboard and PWC engine oil. It is the spec almost every modern outboard and PWC manufacturer requires, and it covers ashless burn, lubricity, fluidity at low temperature, and water-suspending capability. AMSOIL HP Marine, 100:1 Pre-Mix, and 2-Stroke Injector Oil all carry NMMA TC-W3 certification.
Running a non-TC-W3 oil in a 2-stroke marine engine voids the warranty and risks plug fouling, ring sticking, and exhaust deposits.
AMSOIL HP Marine: direct-injected and high-output outboards
AMSOIL HP Marine 100% Synthetic 2-Stroke Oil is the highest-performance pick in the marine 2-stroke lineup. It is engineered for the lean-burn cycle modern direct-injected outboards use, with extra lubricity to fight piston and cylinder wear at the leanest mix ratios. The standard pick for current Evinrude E-TEC, Mercury OptiMax, Yamaha HPDI, and Suzuki DI 2-stroke outboards. AMSOIL publishes test data showing HP Marine outperforms leading OEM marine 2-stroke oils on piston cleanliness, ring-stick prevention, and corrosion protection.
AMSOIL 100:1 Pre-Mix: outboards and PWCs
AMSOIL 100:1 Pre-Mix 100% Synthetic 2-Stroke Outboard Oil is engineered to protect at lean mix ratios down to 100:1 while still working at standard 50:1 premix. It is the standard pick for premix outboards and almost every personal watercraft. The corrosion-control package is sized specifically for the marine environment.
AMSOIL 2-Stroke Injector Oil: value pick for older injector outboards
AMSOIL 100% Synthetic 2-Stroke Injector Oil covers most 2-stroke injector-pump outboards (other than Evinrude on factory-lean settings, which should run HP Marine), snowmobiles, and other recreational equipment. It is the value pick for owners running an older injector outboard who do not need the extra performance margin of HP Marine. Browse the full marine lineup on AMSOIL's marine page.
Bottom line: which AMSOIL marine 2-stroke oil should you pick?
- Direct-injected outboard (Evinrude E-TEC, Mercury OptiMax, Yamaha HPDI, Suzuki DI). Pick AMSOIL HP Marine.
- Premix outboard or PWC. Pick AMSOIL 100:1 Pre-Mix Synthetic.
- Older injector outboard, value pick. Pick AMSOIL 2-Stroke Injector Oil.
- 4-stroke outboard or inboard. Browse the marine motor oil overview for the matched 4-stroke marine pick.
- Off-season storage. Add AMSOIL Quickshot at the last fill before storage.
Save on AMSOIL with Preferred Customer pricing
AMSOIL Preferred Customer membership is $20 USD per year ($10 USD for a six-month trial) and unlocks up to 25% off on every product, with free shipping on qualifying orders. Add the membership to the same cart as your order and qualifying products switch to member pricing on that checkout, with no separate sign-up step. See the breakdown on the AMSOIL Preferred Customer page, or sign up directly through the AMSOIL Preferred Customer enrollment page.
Marine 2-stroke oil FAQ
What is TC-W3?
TC-W3 is the National Marine Manufacturers Association (NMMA) certification for water-cooled 2-stroke outboard and personal watercraft engine oil. It is the spec almost every modern outboard and PWC manufacturer requires. AMSOIL HP Marine, 100:1 Pre-Mix, and 2-Stroke Injector Oil all carry NMMA TC-W3 certification.
Should I use HP Marine or 100:1 Pre-Mix?
AMSOIL HP Marine is the highest-performance synthetic 2-stroke marine oil, designed for direct-injected and high-output outboards including Evinrude E-TEC, Mercury OptiMax, Yamaha HPDI, and Suzuki DI 2-strokes. 100:1 Pre-Mix is the standard pick for older premix outboards and most PWCs, with the rust and corrosion protection a marine environment requires.
What about 2-Stroke Injector Oil?
AMSOIL 100% Synthetic 2-Stroke Injector Oil covers most 2-stroke outboards (other than Evinrude on factory-lean settings, which should run HP Marine), snowmobiles, and other recreational equipment. It is the value pick for owners running an older injector outboard who do not need the extra performance margin of HP Marine.
Can I run a TC-W3 oil at a richer mix ratio than the manual lists?
Yes, in either direction within reason. AMSOIL 100:1 Pre-Mix is rated for ratios from 100:1 down to 32:1. Older outboards typically call for 50:1 premix; newer lean-burn outboards may call for 100:1. Always honor the manufacturer's published ratio for warranty coverage.
How does AMSOIL HP Marine compare with the OEM oil?
AMSOIL publishes data showing HP Marine outperforms leading OEM marine 2-stroke oils on piston cleanliness, ring-stick prevention, and corrosion protection in NMMA TC-W3 testing. The product is designed specifically for the lean-burn cycle modern direct-injected outboards use.
Where do I buy AMSOIL marine oil?
Order online from AMSOIL on the marine page. The matching marine motor oil overview covers AMSOIL's full marine lineup, including 4-stroke marine oil for modern 4-stroke outboards and inboards.
Order AMSOIL marine oil
Order online from AMSOIL's marine page. To unlock up to 25% off, add an AMSOIL Preferred Customer membership to the same cart and qualifying products switch to member pricing immediately, with no separate sign-up step.