Heat transfer systems are provided. The heat transfer systems comprise an object in contact with a heat transfer fluid comprising (a) polytrimethylene homo- or copolyether glycol where from about 50 to 100 mole percent of the repeating units are trimethylene ether units, and (b) a blending component selected from the group consisting of ethylene glycol, diethylene glycol, polyalkylene glycol copolymers of ethylene oxide and propylene oxide, vegetable oils, aromatic compounds, mineral oil, silicone fluids, and mixtures thereof. Objects in contact with a heat transfer fluid in the heat transfer systems include automotive radiators, industrial heat exchangers, heat recovery units, refrigeration units, solar panels, cooling towers, transformers, and heating radiators.