The traction coefficients for a series of hydrocarbon fluids were determined and related to their structural and rheological properties. A continuous relationship was found between the coefficient of traction of the poly(1-olefin) fluids and the number of carbon atoms in the monomer with a maximum at poly (1-butene). A family of gem-dimethyl substituted structures was found to exhibit unusually high-traction coefficients for viscosity index levels.The manner in which certain types of additives affect traction was determined in the development of a formulated traction fluid. Various standard tests show that the formulated traction fluid has very good oxidation stability, provides excellent wear and rust and corrosion protection and offers comparable bearing fatigue life to a conventional automatic transmission fluid. The effect on seals is also similar to that of an ATF.Field tests indicate that the formulated traction fluid will operate effectively in traction transmissions, and conventional automatic transmissions; and will lengthen service life of limited slip differentials and roller clutches.