There are three basic types of coolant: Ethylene Glycol (EG), or conventional coolant, is typically green; Long Life, or Extended Life, Ethylene Glycol is typically yellow; and Propylene Glycol (PG) is typically red and sometimes referred to as �non-toxic� coolant. The term non-toxic can be confusing � all coolants are toxic, and should not be ingested. �Non-toxic� is associated with PG-based coolant because the United States Food and Drug Administration has classified Propylene Glycol as Generally Regarded As Safe (GRAS) in its pure form. The coolant manufacturer adds toxic chemicals to the PG base. Because of its toxicity, keep all coolants away from children and pets and dispose of all waste coolant properly.

PG coolant is not recommended for Power Stroke Diesel engines. Because of its chemical makeup, PG coolants can cause damage to aluminum parts, gasket materials and certain kinds of hoses. It also has a lower boiling point than EG coolant, usually 10 F to 15 F lower. While it may not sound like much, in a modern cooling system with a high output engine a few degrees may make all the difference in the world. Coolants that are methyl alcohol or methoxy proponol-based should also never be used.


According to that article it is ok for gas but not diesel

 

You should assume nothing based on the color of the coolant, you do need to know the chemistry. Zerex (linky) makes G-05 coolant yellow for Ford, light yellow for Mercedes, Orange for Chrysler, and green for Deere & Company. Exact same coolant, four different colors.

I have seen Prestone heavy duty pre-charged diesel coolant that is purple.

Evans waterless coolant is propylene glycol based, is colored blue, and is a lifetime coolant even in diesels.

The coolant in my engine is ethylene glycol based diesel ELC that is red colored.

 

What I said was from that site the guy above mentioned.

 

I will be changing to peak this weekend. Should I remove the block drain plugs and make sure I get all the coolant out? Thanks

 

IMO, yes. You can flush it enough that you can get all the old coolant out, but the block will hold almost two gallons of water that you can not get out without pulling the plugs.

If your intention is to start from scratch using distilled water then you must pull the plugs....unless you are going to do the engine flush with distilled.

 

I just wanted to change to peak its time to change it so I will drain it pull the plugs drain the block flush it with the hose reinstall the plugs and fill it with peak does this sound right

 

Sounds good to me.