Use of synthetic hydrocarbon oils as heat transfer fluids

In a heat transfer system comprising heat source means, heat sink means, a heat transfer fluid and means for conducting said heat transfer fluid between said source means and said sink means;

• the improvement comprising using as said heat transfer fluid in said system a hydrocarbon oil produced from homopolymers, copolymers, or combinations thereof, of alpha olefin monomers having from six to twelve carbon atoms, said oil having a pour point of no higher than -35.degree. F., a kinematic viscosity no higher than 25 centistokes at 210.degree. F., and a flash point of at least 530.degree. F.