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.
Step 1 Place a 5 gallon bucket on level ground.
Step 2 Pour propylene glycol into the bucket, emptying only half of the 1 gallon container into it.
Step 3 Pour half the ethylene glycol into the bucket.
Step 4 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.
Tip: You can also pour each of them directly into your radiator or overflow tank, but trying to estimate a 50/50 water and antifreeze mix is a bit more difficult this way. No harm will come to your cooling system by mixing these two types of antifreeze together.
Warning: If pouring these glycols into your radiator directly, NEVER open the radiator or overflow tank when the engine is hot. Splashing and severe scalding may occur when opening a hot cooling system.
Items you will need: Ethylene glycol antifreeze in 1 gallon container, Propylene glycol antifreeze in 1 gallon container, 5 gallon bucket, Fresh water, distilled is preferred