Fork oil is available with different grades of viscosity; the weight of which determines the response of the fork suspension. Most oil companies supply light SAE 5, Medium SAE 10, and Heavy SAE 20. Simply by mixing equal parts of different fork oils with different viscosity grades, a new mixture can be achieved.
For example, 2/3 SAE 10 and 1/3 SAE 5 will create SAE 7.5
For Harleys and Buell type E, use SAE10
For Suzuki L01, use SAE5
For Honda when ATF, use SAE10
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