A functional fluid comprising a major amount of an oil of lubricating viscosity, and greater than about 0.05 wt-% glycerol. A method of preparing a functional fluid comprising adding glycerol to a functional fluid, wherein the glycerol is not glycerol monooleate. A method of preparing an additive concentrate comprising adding glycerol to a diluent oil wherein the concentrate contains from about 1% to about 99% by weight of said diluent. A method of reducing friction comprising contacting a metal surface with a functional fluid comprising a major amount of an oil of lubricating viscosity and greater than about 0.05 wt-% glycerol.