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Friction Modifiers

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Friction modifiers are added to various lubricants to change their lubricating properties under special conditions. On a molecular level, they have a polarity that makes them want to cling to metal surfaces. In light friction environments, they provide excellent lubrication, but when the friction stress is increased, they a sheared off, and friction can occur. This makes them particularly useful in automatic transmission fluid, the planetary gear sets inside of the transmission have to be clamped on by bands to make the outer ring stationary, and friction is required to achieve that.

What Are Friction Modifiers? Video by Cars Simplified