A method for cooling an internal combustion engine using a reduced toxicity, ethylene glycol and water based heat transfer fluid is provided. A heat transfer fluid is formulated comprising water and a glycol component consisting of ethylene glycol and either propylene glycol or glycerol. Propylene glycol may be provided in an amount between 5% to less than 30% of the total weight of the glycol component. Glycerol may be provided in an amount between 5% to 20% of the total weight of the glycol component. The glycol component is less toxic than 10,000 mg/kg on an acute LD50(rat) oral toxicity basis. The water comprises between 40% and 70% by weight of the total weight of the heat transfer fluid. The cooling system of the internal combustion engine is substantially filled with the heat transfer fluid such that the heat transfer fluid absorbs heat that is produced by the internal combustion engine and releases the absorbed heat to the atmosphere.