Propylene glycol is a viscous, oily fluid which is commonly used in many products. It is often used as a non-toxic antifreeze, solvent (ink jet printer cleaning), and in food refrigerant applications, such as in making ice-cream. For antifreeze applications, we recommend using no more than a 60% by weight solution in distilled water. Water has a high specific heat capacity, so only the appropriate percentage should be use to prevent freezing and boiling. Excessive use of propylene glycol will cause the antifreeze to lose its ability to retain sudden increases in heat and often cause system failure, especially in vehicles. (This is the same rule for ethylene glycol as all) Use the following table as a guide for your antifreeze application.