Extreme Heat is Hard on Your Motorcycle

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David Hilgendorf
by David Hilgendorf
July 17, 2023

Extreme summer heat combined with slow-moving commute, rally or parade traffic can be a big problem for your motorcycle.

As heat intensifies, motor oil loses viscosity and becomes thinner. The oil can become so thin that the engine loses oil pressure and you may hear increased valvetrain and gear noise as the metal parts clatter together. Riding with low oil pressure can damage the engine and the only solution is to shut the bike off and wait until the engine cools enough to restore oil pressure.

Decreased airflow

Air-cooled V-twins get extremely hot and riding in slow-moving traffic makes it even worse. When idling, the heat generated by the front cylinder makes the rear cylinder even hotter. Crawling along barely above idle doesn’t generate enough airflow to keep the engine cool. Add in the blazing heat reflecting off the asphalt and it’s a recipe for trouble.

Heat breaks down oil

It’s the motor oil’s job to protect the engine from exposure to intense heat. The rate at which oil oxidizes, or chemically breaks down, doubles for every 18°F (10°C) increase in lubricant temperature. Oxidation occurs when oxygen molecules attack oil molecules resulting in a chemical reaction that leads to harmful byproducts like sludge and varnish. The faster the oil oxidizes, the sooner it wears out and requires changing.

Additionally, oil thins as it heats up and if it becomes too thin it can’t prevent metal components from contacting during engine operation. Once the lubricant film fails, only a sacrificial layer of anti-wear additives on the components is left to prevent wear. But these additives are designed to deplete with time and use. Once they wear out, your engine isn’t protected anymore.

Ride Hard. Run Cool.®

The normal operating temperature of a motorcycle engine is between 155°F and 230°F degrees Fahrenheit (68°C to 110°C). This range can vary depending on the make and model of the motorcycle, as well as the ambient temperature. In extreme dyno testing designed to create engine heat, we’ve seen cylinder temperatures as high as 383°F (195°C) in an air-cooled Harley-Davidson* V-Twin engine. That means the oil breaks down more than 16 times faster than at normal operating temperature!

AMSOIL Synthetic Motorcycle Oil uses high-quality synthetic base oils that naturally resist thinning and breakdown due to extreme heat and mechanical engine activity. As a result, it forms a thick, strong lubricating film on engine components despite the intense heat motorcycle engines can generate. It also features a robust additive package designed to protect motorcycle engines and transmissions from wear, while improving clutch feel.

Riders who use AMSOIL Synthetic Motorcycle Oil gain peace of mind and protection from the risk of losing oil-pressure and potentially causing severe engine damage, so they can enjoy riding harder, faster and farther all summer long!

Not sure which AMSOIL products are right for your motorcycle? Find the right AMSOIL Synthetic Motorcycle Oil, Oil Change Kits and other products for your Dirt Bike, V-Twin or Metric motorcycle by using our convenient Motorcycle Lookup Guide.


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by David Hilgendorf

AMSOIL Technical Writer and 20-year veteran of the motorcycle industry. Enjoys tearing things apart to figure out how they work. If it can’t be repaired, it’s not worth owning.

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