What is the Best Dirt Bike Oil?

Most dirt bikes use the same volume of oil as a push lawnmower despite making 10X the power. Use the...

July 20, 2021

Like other vehicles, modern dirt bikes make more power from smaller engines. In many cases, only about a quart of oil is responsible for protecting against wear and the devastating effects of extreme heat. Clearly, you want to use the best dirt bike oil to ensure maximum protection and engine life.

This being the AMSOIL blog, we think AMSOIL Synthetic Dirt Bike Oil fits the bill. Read on to find out why.

What dirt bike oil must do

Whether you’re riding the trails near home or competing in sanctioned motocross races, you want to ride as effectively as possible. Maybe that means getting out in front of your buddies on the trail or grabbing the holeshot and riding your way to the checkered flag.

As such, you’re constantly on the throttle, with some dirt bike engines revving as high as 10,000 rpm.

Add a little summer heat to the mix and your engine has a challenge on its hands. Hot ambient temperatures combined with a high-revving engine create severe conditions that can reduce performance and shorten engine life.

Heat stresses your engine

Heat causes metal engine components to expand. If, for example, the piston expands beyond normal tolerances, it can break the lubricant film separating it from the cylinder wall and rub directly against the metal, causing scuffing and wear. Eventually, the piston will fail and wreck the engine.

Cracked dirt bike piston
High stress combined with its lightweight design caused this dirt bike piston to fail.

Minimum oil, maximum stress

Motor oil is your number-one defense against piston scuffing and wear. The oil absorbs heat and dissipates it into the atmosphere via the oil sump.

It should also form a thick, resilient film on engine parts to prevent metal-to-metal contact. Its detergents and dispersants must hold combustion byproducts in suspension and prevent them from forming harmful engine deposits that can lead to piston-ring sticking and power loss. Most dirt bikes, however, hold only about a quart of oil.

Make/ModelHorsepowerQuarts of Oil
KTM 450 EXC-F521.27
Honda CRF450R531.1
Kawasaki KX 450521.0

A minimal amount of oil is asked to perform the daunting task of resisting extreme heat and wear in your expensive, powerful dirt bike engine. The oil had better be up to the challenge or else the engine can wear out and fail.

Most dirt bikes use about the same volume of oil as a push lawnmower despite making 10X the power.

AMSOIL Synthetic Dirt Bike Oil isn’t merely a rebadged automotive oil. We identified the suffering points of modern dirt bikes by working with professional Supercross and Motocross riders. We validated the oil on the track and in our mechanical lab.

The result is an advanced oil that delivers excellent protection against wear and extreme heat in high-revving, powerful bikes. In addition, we designed it to provide confident clutch feel. Riders need an oil that provides not only wear protection, but consistent clutch feel from the time the gate drops until you cross the finish line.

Oils that break down due to heat and stress lead to clutch slippage and sloppy, inconsistent clutch feel, reducing rider performance. Here, too, AMSOIL Synthetic Dirt Bike Oil proves superior, as the test results show.

In extreme simulated-start testing, AMSOIL provided superior wear protection and kept clutch plates looking new.¹

The best dirt bike oil must protect against clutch wear.

You can see the importance of using an oil specifically designed for dirt bikes. Given its excellent wear protection and heat resistance combined with its ability to deliver confident clutch feel, we think AMSOIL Synthetic Dirt Bike Oil is the best on the market and the oil you should be using.

¹Based on dyno testing of a Honda CRF450 dirt bike using AMSOIL 10W-40 Synthetic Dirt Bike Oil and a leading original equipment manufacturer 10W-40 conventional dirt bike oil.

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