Fuel & Oil - OUTBOARDS

Using the correct grade of fuel helps to ensure optimum performance, economy and reliability from your engine. It is important to follow the recommendations for your model engine as incorrect fuel can damage your engine or affect performance.


  • Using fuel that is below the minimum recommended octane may reduce engine life
  • Fuel recommendations are based on engines being set up and tuned to manufacturer's specifications. This includes using the correct propeller to allow engine to achieve recommended maximum RPM under typical load and conditions
  • Leaded fuel is not recommended
  • Fuel that exceeds 10% ethanol is not recommended


  • Use a major brand of automotive unleaded petrol (ULP) with a minimum posted octane rating of 91
  • These recommendations apply to Mercury and Mariner 2-Stroke, 4-Stroke, Verado and OptiMax models unless specified otherwise (ref to "Notes & Exceptions" following)

Notes & Exceptions

Verado Models:

  • Verado 275/300hp - Premium Unleaded Petrol with a minimum 95 octane recommended for maximum performance
  • Verado 350hp - Premium Unleaded Petrol with a minimum 95 Octane Recommended for Maximum performance
  • Verado 400R - Premium Unleaded Petrol with a minimum 98 octane

Engines manufactured prior to 1980:

  • 2hp to 20hp - Unleaded Petrol (ULP) - minimum 91 Posted Octane
  • 30hp & above - Premium Unleaded Petrol (PULP) - minimum 95 Posted Octane

Performance Products will have different requirements, consult your Operation andMaintenance Manual


Pre-Mix Models

Fuel/oil ratio: 50:1 (50 parts fuel to 1 part oil)

Oil requirement:  - Certified TC-W3 2-Stroke Outboard Oiloil measuring jug

                               - Mercury or Quicksilver Premium 2-Cycle TC-W3 Outboard Oil

                               - Mercury or Quicksilver Premium Plus 2-Cycle TC-W3 Outboard Oil

  • 2-stroke oil is normally added to the fuel tank when filling with fuel. 
  • This convenient oil measuring bottle is great for calculating oil required for various volumes of fuel            - order part # 67-886696 from your authorised Mercury dealer

Pre-mix is generally used in the following 2-stroke models

  • All 2hp to 30hp models
  • All models up to 225hp manufactured prior to 1984

Autoblend Models

Oil requirement: - Certified TC-W3 2-Stroke Outboard Oil

                              - Mercury or Quicksilver Premium 2-Cycle TC-W3 Outboard Oil

                              - Mercury or Quicksilver Premium Plus 2-Cycle TC-W3 Outboard Oil

  • Autoblend models have an oil reservoir mounted inside the boat that automatically blends oil with the fuel at a constant ratio of 50:1
  • 2-stroke oil is added to the reservoir and does not need to be mixed with the fuel (unless required for running-in)
  • Autoblend was used on some 35hp to 115hp models manufactured between 1984 and 1988

Oil Injection Models 

Oil requirement

Mercury/Mariner V6 models have an additional oil reservoir mounted in the boat


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