Antifreeze coolant-Ethylene vs Propylene

I did a write up on the difference between the two in the context of RV Plumbing Antifreeze (not exactly the same in automotive). It still explains the plusses and minuses of Propylene Glycol if used in plumbing, HVAC or automotive.
Link

Moved from Forum Technical Support

Since you are in California, you might check whether there is an environmental regulation requiring the use of propylene glycol, or special handling of ethylene glycol. Dealing with ethylene glycol toxicity is why alternative formulas have become available with a propylene glycol base.

We went through a brief period in this state when auto service centers were required to "recycle" ethylene glycol antifreeze by filtering and reusing. Most service simply responded by refusing to do antifreeze service and the regulation soon got repealed.

FWIW, the greatest source of ethylene glycol in the environment in most parts of the U.S. is not automotive products, rather the runoff from airport de-icing stations.

Put the one in that your manual says to use for your vehicle. Changing the type can cause problems. I NEVER put anything in my RV or personal vehicle except what is listed by the manufacturer. Especially when it comes to the antifreeze. Should be listed under the hood on one of the spec labels.

What rockhillmanor said!!! Do NOT go switching or you MAY be asking for trouble, don't ask me how I know...........

I agree that the best option is what the manufacturer recommends. However, ethylene glycol must be disposed of properly - it tastes sweet and is highly toxic to wild animals, pets, and maybe even kids.

Thank you everyone for your input. I do wish it was as easy as 'looking in the manual' or 'under the hood'. Even when I took it to the Cummins dealer many years ago, they did not note 'which' antifreeze they put in *ethylene or propylene (and I didn't know any better, nor question them).
Cummins, in their manual 'Tech Dept.' state that the ISC engine should use either (ethylene or propylene). I again contacted today and was advised I should switch to the OAT base antifreeze.
Bottom line...I think I will probably switch to the OAT base antifreeze. I've noticed that there has been a few articles on the web showing the steps to take to accomplish this. Again, thank you to all...