UTTO vs TO-4 Fluid #OilChat 63

TO-4 Fluid should not be confused with Universal Tractor Transmission Oil (UTTO).  Although both TO-4 fluids and UTTOs are designed for wet brake applications, they are NOT interchangeable since they have different physical and chemical characteristics – frictional properties in particular.

TO-4 Fluid originates from the Caterpillar TO-4 Transmission Oil specification. TO-4 has become a standard term used within industry for this specific type of additive/fluid. Construction machinery, for which TO-4 fluids are intended, is normally much bigger and heavier than agricultural equipment. A high level of friction is therefore required to ensure that these heavy machines can stop on steep inclines, such as access roads down open cast mines. This necessitates TO-4 fluids to have a high coefficient of friction.


UTTO, also referred to as Tractor Hydraulic Fluid (THF) or Transmission, Differential and Hydraulic (TDH) fluid, is mainly used in agricultural applications. They are however sometimes recommended for construction machines, such as Bell ATDs. Tractor size and weight are limited since they need to use public roads, hence less friction is required to stop agricultural equipment. UTTOs therefore have a much lower coefficient of friction than TO-4 Fluids.

A wrong fluid in wet brake applications will affect fluid/brake surface interaction and decrease braking performance with possible catastrophic consequences. If an UTTO is used where a TO-4 fluid is specified, braking efficiency will be reduced, resulting in increased stopping time and distance. Using a TO-4 Fluid where a UTTO is recommended will cause very bad vibrations and brake chatter, leading to heavy wear and failure of components.

Acquaint yourself with the fluids recommended by your equipment manufacturer, have them on hand and pay attention to tractor and equipment service intervals. If in doubt our experts are at your disposal, ready to provide you with advice and to answer any questions you may have. For more information mail us at info@bcl.co.za