How To Clean Oxidized Aluminum Motorcycle Engine

With the entry of Harley Davidson into the motorcycle industry, aluminum has significantly been used to make motorcycle engine blocks due to its strong and lightweight features.

With time, aluminum undergoes an oxidation process in which the metal surface reacts with oxygen to form a gray cast layer on the exposed bike engine parts. Accumulation of the oxidized layer slowly discolors the shiny appearance of the engine block.

When cleaning the oxidized aluminum motorcycle engine, you may need to take caution to avoid damaging the engine parts with solid water jets used to clean cast iron blocks.

We recommend one to use vinegar and baking soda to clean oxidized aluminum engine block cases in combination with other methods as discussed below in this article.

Required Materials for Cleaning Oxidized Aluminum Motorcycle Engine

You need the following materials to make your cleaning easy. Some can be modified at home, such as the cloth.

Required Materials
  • Vinegar
  • Plenty water
  • Baking soda
  • Safety gears
  • Damp cloth
  • Metallic scrubber
  • Lemon juice and salt
  • Anti-oxidation products

How To Clean an Oxidized Aluminum Motorcycle Engine

You don’t have to scrub your engine block to remove oxidation from aluminum engine. Scrubbing will dent your engine, reducing its quality. The following steps will guide you in cleaning the oxidized motorcycle engine.

Clean an Oxidized Aluminum Motorcycle Engine

Step 1: Cleaning the aluminum engine surface with water

Clean the outer surface with hot water with soap detergents to remove dirt and oil layers. Some oxidation layers are not profoundly attached and can be removed by applying soap and hot water.

You may prefer to use a water jet to increase the efficiency due to the pressure on the dirt. If the oxidation is removed at this stage, you have achieved your goal. For the permanently attached oxidation, progress to the next step.

Step 2: Clean using vinegar and baking soda

Being a reactant with oxidizing agents, the chemical composition of vinegar makes it suitable for cleaning aluminum. The acetic acid in the vinegar and sodium bicarbonate in baking soda reacts with aluminum oxidation.

Mix three teaspoons of vinegar in one cubic meter of water and leave to a boil. Dip the small parts in the mixture and leave for a few minutes until bubbling stops. When dealing with large parts of the engine block, soak a cloth and use it to scrub the surfaces thoroughly.

Clean using vinegar and baking soda

We recommend that you don’t use vinegar and baking soda together for better results. Be careful to rinse the remaining vinegar water with running water and dry cloth.

Step 3: Use a buffing wheel

If vinegar-based cleaners don’t achieve the target, a buffing wheel is the best choice. Apply water and soap detergent to the engine surface and scrub thoroughly. Scrub off the remaining oxidation using a buffing wheel, taking care not to scratch the air cooled engine fins.

Step 4: Application of chemical oxidation removers

Meguiar’s M4916 Marine is one of the best chemical oxidation removers that offers a corrosion resistance surface. These solutions contain chemicals that react with the oxidation leaving a clear shiny surface.

Apply the solution and leave it to dissolve the oxidation for 10 minutes and then rub it with a clean cloth. Please leave it to dissolve for not more than 5 minutes to avoid damaging the cast aluminum when applying on it.

chemical oxidation removers

Apply an anti-oxidation protective coating to prevent further corrosion upon cleaning all the oxidation.

Step 5: Clean the internal parts using marvel mystery oil

With successful cleaning of the outer surfaces, you should check the internal parts of the engine block. Marvel mystery oil contains acidic components that help dissolve rust inside the engine.

Mix the mystery oil with your preferred engine oil and allow it to flow into the engine through the intake manifold. The oil will slowly dissolve the rust in the motorcycle engine components and then empty the oil during the next oil-changing period.

How do you Polish an Aluminum Motorcycle Engine?

Polishing aluminum depends on the type of aluminum metal and the surface area to be polished.

The best polishing methods involve carpet cleaner, diamond sharpener, and hand polisher. Dry the surface with soft dry linen and apply the polish onto the aluminum surface with a cloth in a circular round in the same direction. 

How do you Polish an Aluminum Motorcycle Engine

Take time to polish the aluminum cooling fins on the motorcycle as they are also prone to corrosion.

What’s the Best cleaner for Aluminum

Different cleaners are best suited for cleaning aluminum based on the type of aluminum metal and the part being cleaned. Listed below are among the best cleaners for aluminum surfaces.

1. Aluminum restoration solution cleaner

AL-New restoration solution is the best aluminum cleaner available on the market. They contain mild acid, which helps dissolve aluminum oxidation giving back a shiny appearance.

Aluminum restoration solution cleaner

One wash with aluminum restoration solution is enough to give you a long-lasting corrosion-resistant surface.

2. Car-guy wheel and tire cleaner

If you are looking for the best aluminum wheel cleaner, Car-guy cleaner offers the best one, giving your wheels and tires a shiny appearance.

Car-guy wheel and tire cleaner

3. Sonax 230241-wheel cleaner plus

Sonax wheel cleaner gives you a pocket-friendly package that performs well on your wheels.

The solution has no acidic properties with a well-balanced pH that does not damage your aluminum wheels.

Sonax 230241-wheel cleaner plus

4. CLD-107 premium blue wheel and rim cleaner

It comes in the form of a spray and does not require rinsing after spraying. You don’t need to scrub off the dirt and layers on the wheels. CLD-107 premium dissolves the dirt and peels off, leaving a shiny surface.

CLD-107 premium blue wheel and rim cleaner

Does Road Salt Boost Aluminum Oxidation in Motorcycle Engines

Road salt boosts aluminum oxidation in motorcycle engines. Road salt is used to clear and melt ice on roads. Motorists benefit from the road salt but suffer from accelerated rusting of the aluminum surfaces and fading away of the paint.

The aluminum oxidation process involves the movement of electrons speeded up by the salty water on the roads leading to faster rusting of the engine block.

To reduce the process of aluminum oxidation, wash your motorcycle thoroughly with a lot of water. In extreme cases of aluminum oxidation, apply anti-corrosion treatment such as ACF-50.


At times, cleaning an oxidized aluminum motorcycle requires more than just water and detergents. The gray cast layer on the surface of motorcycle engines can be removed and achieve a shiny, spotless appearance. 

With the above guide, it is possible to clean up the oxidation in the comfort of your motorcycle garage. It is advisable to purchase the required materials from trusted sources to avoid purchasing products harmful to your engine.

In the case of chemicals, ensure you practice care and caution to avoid harming yourself and damaging the motorcycle engine.

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