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2005 Cadillac CTS-V
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Discussion Starter #1
Quick question: I've ordered the all aluminum alradco radiator for my 2005 CTS-V which I plan to install next week but never having done radiators before would like to know what good quality coolant you'd recommend for our cars. I'm assuming a 50/50 mix is the way to go but just don't know what brands are good and which I should steer away from. Any recommendations?
 

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Discussion Starter #2
Also, I'm assuming the standard GM "orange" coolant fluid is fine, unless someone tells me otherwise. My local Cadillac dealership sells it for $20 a gallon (the concentrated stuff). Do you still need to use distilled water to make the 50/50 mix or am I just showing my age?
 

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2005 CTS-V
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I have aluminum Ron Davis Racing radiator and I run DexCool mixed at 50/50. I use either distilled water or deionized water. I believe you can use tap water unless you live where the water contains a lot of minerals e.g. West Texas well water.
 

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Discussion Starter #4
DexCool by Prestone (& "approved" by GM) or the DexCool radiator fluid (don't think they call it that) sold by GM directly or doesn't it matter?
 

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Makes no difference. DEX is a type, not a brand.

...FWIW, it makes no difference weather you use DEX or conventional to begin with.
 

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Discussion Starter #6
Well, maybe. All I know is that the guy who custom builds these all aluminum racing radiators said I absolutely must a). use distilled water and NOT tap water (if I'm mixing from the concentrate) and b). should use DexCool
 

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According to a GM Technical Service Bulletin regarding the stock cooling system:

Water Quality
The integrity of the coolant is dependent upon the quality of DEX-COOL(R) and water. DEX-COOL(R) is a product that has enhanced protection capability as well as an extended service interval. These enhanced properties may be jeopardized by combining DEX-COOL(R) with poor quality water. If you suspect the water in your area of being poor quality, it is recommended you use distilled or de-ionized water with DEX-COOL(R).
 

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Discussion Starter #8
Got it - and do you think you get a stronger mix by doing the mix yourself or is buying the pre-made 50/50 mix just as good. I saw some complaints about the pre-mixed stuff being weaker than mixing a gallon of the concentrate yourself.
 

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2005 CTS-V
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I have never tested the 50/50 pre-mix, nor used it to fill a system, but I keep a gallon of the pre-mix on hand for topping off the system. I only buy the concentrate because it is easier to haul home. I have one of those under-the-sink, reverse osmosis, drinking water systems in my kitchen that supplies de-ionized water.
 

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'05 CTS-V
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You can also buy distilled water at most grocery stores or Walmart for about a buck a gallon.

Depending on where you live (which isn't on your profile) you may or may not need a 50/50 mix. You can find info online that will show you the freezing and boiling temps of various mixes. Water is actually a better heat transfer medium than coolant; the coolant adjusts the freezing and boiling points, lubricates the water pump, and reduces corrosion.
 

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I have always found that the concentrated Dexcool is less expensive than the 50/50 when you do the math. I pesonally use my RO water to mix with the dexcool. We have some of the hardest water here in AZ.
 

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Discussion Starter #12
Thanks guys - I ended up buying two gallons of the concentrated Dexcool (that's all my autoparts store carried - and yes, it is cheaper going that route) and two gallons of distilled water from the grocery store. My Alradco radiator turned up today - what a work of art. Kudos to Pete for a high quality product - this will undoubtedly last a lifetime...it's built like a tank and compared to the 6lb plastic piece of junk it's replacing it's almost laughable. The attention to detail is amazing - including the packaging. I don't think I've ever received a car parts package so carefully packed. So it goes in tonight together w/new hoses, belts, etc. and a full flush.
 

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Discussion Starter #13
I am hesitant to even raise this question as it seems quite contentious but here goes: now that I have my new alradco radiator installed and running cooler than stock (about 10-15 degrees) is it even worth considering installing a 160 or 180 thermostat as a replacement to the stock 195 degree? The ONLY reason I'm considering it is because, as I understand it, the thermostat only starts opening when the engine coolant temp (NOT the radiator temp) reaches 195. If that's true, I kind of like the idea of having the thermostat open earlier to let all that "cooler" coolant in my aluminum radiator circulate through the engine block. I realize you are supposed re-program the fans to come on earlier but seeing that they only come on at idle and go off once you start moving again, I am more interested in keeping the coolant temp down while I'm actually driving (racing) the vehicle - hence the question about the pros & cons of a 180 or 160 thermostat? Is it worth it? I'm thinking probably not a). because I live in a coolish climate (Michigan) and b). the car is already running 10-15 degrees cooler than stock but, of course, I have this nagging feeling that perhaps I could do a wee-bit better. Your thoughts/recommendations?
 

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You want to keep the factory temp when you run lower temps your engine will build up moisture in the oil because it's not getting hot enough to boil it out. If you're only racing the car and the oil gets changed all the time you could do it but if you DD it at all don't do it.
 

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I agree with mac_henderson2001. I have the Ron Davis Racing radiator with the stock thermostat. That combination translates into cooling capacity that keeps the engine coolant temperature at 194F or below, no matter what. And that is here in Houston, Texas. My oil temperature on the highway runs between 216F to 220F which is just adequate to eliminate the water byproduct of combustion that would otherwise accumulate in the oil. There is no way I would do anything to keep the engine any cooler. If I were tracking the car, I might consider an oil cooler if, and only if, I installed a bypass valve to eliminate the cooler circuit for the street.
 

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Discussion Starter #16
Interesting - I just did a round trip to chicago and my coolant temp was a steady 194F. The oil temp ran about 20 degrees hotter. I think you guys are convincing me to leave it alone.
 

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Correct me if I'm wrong, but wasn't there something about having to adjust the fan speed to compensate for the thicker aluminum radiator? I seem to remember people talking about having some hotter temps than expected after the swap because the fans were not adequately cooling the new thicker radiator. Asking because this may be my next project.
 

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Discussion Starter #18
That question/issue never came up for me during my research, purchase and installation - and I waded through a lot of threads on this list and others but it could be an issue - I just didn't run accross it. I know there is talk about the same company (I think) eventually offering a slim version of the fan/fan shroud (the stock one is a very tight fit) and I don't know if they will be offering that w/a different type of fan and/or speed. The one thing I will say that I don't remember happening w/my stock radiator is that after I've been driving around for a while and I stop the car to run into a store, etc. when I get back in the car and start her up the fans switch on straight away (and then turn off once I start driving again). I don't remember that happening w/my stock radiator except on hot days and when the car was really hot. I've been ignoring it so far because the car is running at 194F when driving around which is 10-15F lower than stock. Not sure what that's about...
 

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Discussion Starter #19
Correction: I'm not noticing the fans coming on as much anymore so I'm gonna say this whole upgrade has been a success, without any glitches/complications. So, no, in my case I am not experiencing any hot spikes in the coolant temp as a result of the thicker radiator.
 
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