Propylene glycol and ethylene glycol are both used as antifreeze for cars and trucks They are chemically similar in many respects, with propylene glycol considered to be a safer alternative than its ethylene cousin; however, ethylene glycol has better heat transfer properties. Although propylene glycol antifreeze has less coolant ability and is less toxic than ethylene glycol, mixing them won't lessen toxicity or have a major effect on cooling ability.
Place a 5 gallon bucket on level ground.
Pour propylene glycol into the bucket, emptying only half of the 1 gallon container into it.
Pour half the ethylene glycol into the bucket.
Add in approximately 1 gallon of fresh water, using distilled water as an ideal choice.
Pour this 50/50 mixture into your radiator or automotive/truck overflow tank until full.