Yes, Ethylene glycol and Propylene glycol are very similar chemically, therefore, can be mixed without any bad consequences for the engine.
Ethylene glycol (IUPAC name: ethane-1,2-diol; Chemical formula C2H6O2) is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid. Ethylene glycol is toxic, and ingestion can result in death.
Gasline antifreeze is usually just isopropyl alcohol. Many drugstores sell 97-percent isopropanol, and if you put six ounces of it in a 20-gallon gas tank it will do the same thing as Heet (or whatever brand you like) for less money.
Read Haynes 1993-2004 Antifreeze/cooland - general information: Warning 1: Use only "ethylene-glocol" (green/blue). Do NOT use propylene-glycol (yellow/red). From 2002 long-life-special-glycol (HOAT) are used, and can not be mixed with other types of antifreeze.
Phosphate-free ethylene glycol coolant mixed 50/50 with water
'Regular' or 'traditional' ethylene glycol antifreeze with silicate type corrosion inhibitors (sometimes called green antifreeze) mixed 50% with distilled water is the OE fill.
Well, when mixed in an ideal solution with water, it has a relatively high boiling point and low freezing point. Also, it doesn't cause rust/corrosion.
A Ethylene glycol antifreeze coolant should be used (Mopar coolant) and mixed with 50/50 with distilled water. Another coolant that is pretty good is the Zerex G-05 antifreeze (approved by Daimler-Chrysler).
Both ethylene and propylene glycol possess many characteristics that make them ideal for use in heat transfer systems where protection from freezing is required. Desirable properties include high boiling points, low freezing points, stability over a wide range of temperatures, and high specific heats and thermal conductivities. Furthermore, used with an appropriate inhibitor, glycols demonstrate a non-corrosivity that may substantially prolong system life. Ethylene glycol based solutions work well in most anti-freeze applications because of their excellent heat transfer efficiency. The low viscosity of ethylene glycol allows systems to operate at lower minimum temperatures and is more energy efficient due to its reduced pumping requirements. The primary drawback to ethylene glycol is that it is listed as a "toxic chemical" under SARA, Title III, Section 313, due to its acute oral toxicity. Inhibited propylene glycol should be used for freeze protection where direct contact with foodstuffs or incidental contact with drinking water may occur. Although propylene glycol is generally recognized as safe (GRAS) by the FDA, it is not intended for human consumption. Hope this helps your question.
Ethylene glycol mixed up to 50% with water, lowers the freezing point of the mixture, while remaining an excellent heat transfer medium. It protects the engine from either freezing or from overheating.
Read the owner's manual and buy any antifreeze that meets the requirements listed. The manual calls for Ford Premium Cooling System Fluid, but any water/ethylene glycol based antifreeze solution should be OK. Use the regular green antifreeze, mixed at least 50/50 with water, but never over 70% antifreeze, or just buy it pre-mixed. Make sure it is safe to use with aluminum engine parts. I use Prestone.
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Coolant recommendations and cautions: The recommended mixture is 50/50 ethylene-glycol and low mineral content water. Never use pure antifreeze. Only Mopar Antifreeze Coolant, 5 Year/100,000 Mile Formula (glycol base coolant with corrosion inhibitors called HOAT) is recommended. This coolant offers the best engine cooling without corrosion when mixed with 50% distilled water.