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2004 Deville DTS
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Discussion Starter · #1 ·
My 2004 Deville DTS (engine code 9) is running fine but I think there may be a problem looming. Last year I tried to change the antifreeze by removing the lower radiator hose. Approximately 1 gallon drained from the 3.25 gallon cooling system. Did not see a practical way of flushing the old antifreeze out so I just added 1 gallon of 50/50 GREEN antifreeze. I recently read that mixing Dex Cool and green antifreeze with cause it to gel. I have a few question that I hope someone can answer:
1. Best way to flush cooling system
2. Should cleaning additive to use? If so what brand
3. Would installing Prestone Flush N Fill make this job easier
4. Would installing a Moroso radiator hose filler help.
5. What is the ID of the upper radiator hose
 

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the correct way is to drain fluid as much as possible, then fill with water, then run for a bit to mix the water in, then drain again, then add more water, then run again, then drain again, etc - until you've basically got only water coming out... then add in your green fluid...

well i'm not sure if that's the correct way, but that's how I would do it...
 

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2004 Deville DTS
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Discussion Starter · #3 ·
Hi Chris, Thanks for taking the time to respond to my problem. I wanted to avoid the procedure you described, too time consuming. Many years ago on a different car I installed a Flush N Fill tee which worked out very well. Do you think this tee fitting, installed before the heater core will speed up the flushing of my contaminated antifreeze?
 

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i've never heard of that before... but i guess it's worth a try...

maybe start another thread simply asking what's the best procedure for changing from dex to green

you might get better response with just that simple question
 

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No one bothered to point out that this is a 2006-2012 DTS forum. It is not intended for questions related to earlier models (2004 in this case).
 

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2011 DTS Platinum
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One more point...
Once you have put green in it... you have contaminated the entire cooling system.
you might as well keep using green and go to a 2 year change interval... instead of what the book says for Dexcool...
 
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