I know there have a been a couple of discussions about this, but when I searched I didn't see an actual thread.
Just wanted to share this little bit. I have in front of me a gallon of Prestone "Dexcool" coolant (ORANGE), a gallon of O'Reilly's generic coolant (CLEARISH), a gallon of Mopar coolant (RED), and a gallon of Ford coolant (YELLOW). Our green stuff comes in bulk and feeds through a gun.
1 - The Prestone guys have done a great job marketing, as I always thought that it was the real deal GM stuff.
2 - The Mopar and FoMoCo stuff are similar ingredients, with ethylene glycol being the first ingredient, but are slightly different after that. I am guessing these are just additives.
3 - The O'Reilly's coolant and the Prestone coolant appear to be exactly the same, accoring to the ingredients. They also say they can be used in any vehicle, any color, blah blah, but when you read the fine print, that is only after a full drain and flush.
I know that you can pour the Prestone product into a GM car with "orange" coolant and it will not cause anything bad or strange to happen, as this is what we have been doing here since I started in June 2005. I am curious what the ingredient list on the genuine GM coolant is. I am also curious if you can add the Prestone orange stuff to Fords and Chryslers with non-green coolants without any bad side effects. I am guessing yes. I think you just can't mix ethylene coolant with propylene coolant.
All that being said, I am going to start topping vehicles that are red or gold with the generic clear O'reilly's stuff from here on out, if anything blows up I will update you guys.
4 - I still think if it came with EG, stick with that, and if it came with PG, stick with that. The performance is virtually the same, price is close, and availability is not an issue.
5 - DO NOT put "works in any car" coolant into your green coolant without flushing it totally first. It is most likely EG which will not like your PG.
6 - Use Distilled water!
7 - Apparently the sludge I have found in systems is a product of phosphates in the coolant and solids in the water added.
8 - I don't know about effects on seals , if any, yet.