What % antifreeze for anti-corrosion use in copper/aluminum loop?

For starters, I am aware that all copper is better and snazzier and all around awesome. However, i do not have (and do not have money for) a copper radiator such as i want. When i do, i will buy one. For now, it's aluminum, so please do not simply say "OMG buy copper!".

That said, what percentage of antifreeze do i need to use to prevent corrosion issues? Right now i'm running ~45%, which i'm sure is plenty but may be too much. I'd like to use less to improve the thermal properties of the coolant.

I have a ~25*c delta between coolant temp and core temp, which seems like rather of a lot. Coolant temp to room temp is ~4-5*c. I did a re-mount and it's still in that area. It is worth noting that it's a on e1200, almost certainly a CPU with TIM between core and lid rather then solder.

Woah, 45% antifreeze??!!??

I never had corrosion. I dont believe anti-freeze can prevent corrosion but it can slow it down. Maybe Im wrong here though.

If it does, and someone can enlighten you on the situation, then run what is needed.

If it wont help prevent it, run as low as you can as water w/ less antifreeze will transfer more heat out. I know I used Water Weter used just above the amount suggested (4 oz per gallon I think?)

20% antifreeze for corrosion protection. More will decrease heat removal efficiency. In the automotive world you should change antifreeze every 4 years ( Some sites say 2-3... But I'll stay with 4). The corrosion protection lessens by then.

Just dont mix/match metals

sry i have to say this ! but there is alwais an issue possible. You want to take risk with your 2000$ computer ?

5% concentration coolant
1:20 ratio

edit: looks to be more with antifreeze.

change @ 6month
clean @12

never had so much as a pimple on anything myself.

but it depends on what proportions of metals and how much powers being delt with in electrical terms.

if youve proportionately more alu at the rad end it will probably be tickety.

Honestly the amount of corrosion happening isnt THAT big of a deal. If you open up your loop every 6 months, I dont see there being a big issue personally. If your radiator is mounted somewhere other than over critical parts, it really shouldnt be an issue. I honestly cant see a waterblock corroding enough in 6-12 months that it would cause you problems.

Also, aluminum doesnt corrode nearly as bad as say iron or something of the sort. Id run a concentrate antifreeze (such was Water Wetter, or something similiar) and SLIGHTLY higher amount than indicated (5 oz per gallon of water, about 4% or go 5% as indicated above).

More like my $200 computer. I water cooled the cheap box

20% sounds good, i shall add more water and see what that does.



Antifreeze does prevent (or stall, at least) corrosion, how exactly it does it i don't know.
I do know that running straight water in an engine with an iron block and an aluminum head will kill the head in fairly short order (I've replaced a dozen or so in the last ten years).

15% to 20% is what i've read and would go for. anything higher and you start to degrade the cooling ability of the water.

It is the 5-10 corrosion inhibitors (zinc oxide, nitrites, chromates, hexamines, etc) that are in all commercial antifreezes that prevent corrosion.

What is interesting, is that "Glycol based systems, using Propylene Glycol or Ethylene Glycol, without any corrosion inhibitors or additives, are more corrosive and aggressive than water alone."
http://www.glycol.ca/inhibitors/inhibitors/inhibitors.html

And 20% is what most car, etc sites will quote as being protective for couple years as that maintains a high enough inhibitor concentration, then need to change antifreeze since inhibitors loose effectiveness over time.

You could just run 3% concentrated corrosion inhibitors and 97% water like others said, if you could somehow find them. Water wetter is one, but some have said it gunks blocks up, dont know myself, never used it, but it does work in part by coating metal.

I went through this for 2 years when using copper rad and aluminum waterblock (black pearl). I looked into concentrated, but gave up looking and always just ended up using 15-20% pentosin. At 15-20%, just decreases the thermal cond of water from .6 to .53, only made ~2C higher load temps on mine when testing vs pure distilled.

Guess Ill see what my 10% radiator fluid has done for my rad these past few months here real soon. Need to swap my GTZ out for this Heatkiller 3.0 lt.I also plan on changing my mcp-600's to 655's ( one vario and one rev. b)

What we need to think about and possibly find a solution for the OP is we need anti-corrosive properties, not anti-boiling and anti-freezing properties that standard car antifreeze gives you.

That said, all I know is VW and Toyota dealership antifreezes are most recommended by watercoolers. More pure etc.

Think Toyota is Blue, and VW is red.

I thankfully don't worry about such, but thats my input.

I was always told G11 (which is blue) or now G12 which is red.
coolants for motor sports flavour.

its also the 5% dose which doesnt turn the distilled into glycol syrup or coat everything in a film of insulating crud as a matter of functionality.

best stuff I tried G11

Edit: think chilled PC sell it and decant it without the branding premium.

I think 15-20% if using regular auto zone-type green stuff. I've not looked into it enough to know what G11 or G12 even is, but if you can use it with 5-10%, so much the better!

Mixing of metals is no big deal if done properly. http://www.ocforums.com/showthread.php?t=542442