So, I guess what does one really get out of OEM spec-ed coolant? If you run Dex, all of us agree, 10 years/100K without a flush seems a bit, eh, not ready to believe? Safe to still flush and re-fill.... So if you switch to green, in the end, I bet the performance is no different. Keep in mind, the 3100 engine had been though both green and Dex from the factory (depending on the year of the car). For a street car (non-actual race car), I am certain any part store coolant would suffice.

Or is your concern more towards mixing Dex with "generic" green? If that is the case, I can understand that a bit more. It is changing the overall chemical make up by NOT being consistent. We'll see how my daily handles this experiment hopefully in 1-2 or more years when I flush it.

 

I guess my biggest concern is with my newer vehicles and less with the Monte. The green stuff is fine for iron blocks and older cars, but a lot of the newer materials that engines are made out of should really stick with OATs and factory spec'd coolants.

 

I completely agree with using what the manufacturer suggests. But here's where I get mixed ideas. The only thing I can honestly say changed in the vehicles since the 1980's
Is the got rid of brass radiators and heater cores. Aluminum is being used more in its place but was still been used for decades. As for the plastic parts I can't say either way what effects one might gave over the other. Things have come a long way, I can still remember that international (Scout, Harvester ) had lifetime anti-freeze and didn't need changing. 😆

 

When I still had my old truck, I was concerned about mixing yellow with green. I'd gotten yellow by mistake and had never heard of it before. Everywhere I tried find out got me the answer: Yellow or universal mixes with all other colors but orange. I didn't even know about dexcool until I got this monte...I'd never heardof orange coolant or blue for that matter...and I guess there is a blue out there unless someone was being facetious. I just took the yellow back and got the green to be on the safe side. Found a video and apparently the green with the dex makes a brown sludge.

I"m paranoid, so even though I wanted to mix my own dex (much cheaper) I didn't want to start out with one of the green containers for fear of not rinsing it well enough, or go through the hassle of adding a litle water, then a little dex...I didn't realize how much I'd have to use in the long run, at the time I didn't know I'd bought a car with a cracked radiator. I didn't know it would take a few visits to prove it, either, and once they pressurized and ascertained, they told me to just keep adding dexcool to the reservoir until the appointment. All that aside, I bought the first jug of 50/50 at Wal-mart. Then it was Napa where I'd gone to get the second, thinking I could buy the concentrate and mix my own and have two gallons. That was where I got the tap water warning that headed up this thread.

I've still got most all of my second gallon of 50/50 left, and I've been using what they mixed for me to get by until the second R&R which is Friday.

 

Using what the manufacturer recommends is most of the time the best action. You usually get predictable results (being reliability). As for the newer materials in the newer cars in your fleet, I'm curious what materials they use where green is a problem (not saying it is or is not). My understanding of Dex was that it supposedly promoted a longer lifespan before requiring a coolant flush.

As you mentioned, cars like our Montes and my daily (Grand Am), they have nothing that Dex and Green have issues with. And the LIM gasket failures have nothing to do with Dex (it's the fact that plastic gaskets moving coolant fail because it's plastic and gets brittle).