How to Use Seafoam Motor Treatment for an Outboard

Written by rex molder
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How to Use Seafoam Motor Treatment for an Outboard
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Seafoam Motor Treatment is a popular brand of engine cleaner used in two-stroke, four-stroke and diesel engines. Although today it is used in all types of engines, it was originally developed specifically for outboard boat engines. Over time, fuel and oil leave behind residue in the crankcase, around the pistons and in the carburettor jets. Seafoam's purpose is to dissolve this residue. After the treatment, you should notice an improvement in the motor's performance.

Skill level:
Moderately Easy

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Things you need

  • Can of Seafoam Motor Treatment
  • Fuel can
  • Fuel
  • Measuring cup
  • Motor oil (for four-cycle engine)
  • Oil filter (for four-cycle engine)

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    Two-Cycle Engines

  1. 1

    Add Seafoam only to a near-empty fuel tank. This is to ensure you get the proper Seafoam/fuel ratio.

  2. 2

    Prepare your normal gasoline/oil fuel mix. Add 56.7gr. of Seafoam per each gallon of fuel.

  3. 3

    Pour the fuel mixture into the motor's gas tank.

  4. 4

    Start the motor and operate as usual. The Seafoam will dissolve deposits as the fuel mixture passes through the motor. A good indication that the Seafoam has done its job is a reduction in smoke produced by the motor.

    Four-Cycle Engines

  1. 1

    Drain the oil from the motor and change the oil filter.

  2. 2

    Replace the engine oil, and add 44.4ml. of Seafoam for every qt. of oil you added. The Seafoam mixes with the oil and dissolves sludge in the crankcase and from the lifters.

  3. 3

    Add 28.4gr. of Seafoam per gallon of fuel to the fuel tank. It's best to do this when the fuel tank is nearly empty to ensure you get the proper Seafoam/fuel ratio. The Seafoam will dissolve residue in the fuel lines and carburettor jets.

  4. 4

    Operate the motor as normal, but check the oil frequently. Seafoam will cause the oil to get dirty faster than usual. When you see that the oil is dirty, change the oil and filter.

Tips and warnings

  • You can also add Seafoam to gasoline to stabilise it for up to two years.

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