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2004 Forester 4EAT
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Discussion Starter · #1 ·
I decided to drain and flush the wife's radiator today. I drained it via the drain valve, (I know, there are faster ways), pulled the top hose off of rad., and hosed out motor. I seemed to get about two gallons out. When I filled it, I poured a gallon of distilled water into the rad, added coolant conditioner, and then proceeded to add coolant. I got about 8 oz in it. 8-9 quarts came out, and 4-5 went back in.:icon_eek: I figured there must be a bunch of air trapped, so I ran it with the cap off until the t-stat opened. I squeezed out air, added a little more, blah, blah. It still didn't take much more. I am afraid to drive it anywhere. At best, I didn't get it drained all the way and now my mix is WAY too watery. At worst, I have a huge bubble somewhere. And yes, I did have the heat on while running. Thank you in advace, my Subaru Gods.

Edit: I didn't exactly measure what came out, but it sure looked like more than one gallon!
 

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Discussion Starter · #3 ·
Yes I did. I'm thinking it's full, just now way to diluted.
 

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when i drain/flush mine, i go so far as to take the lower hose loose to get extra coolant out. fill with 100% non-diluted antifreeze first. top off with water. if you look at cooling system capacity this will give you about 2/3 or 66% concentration which is good. some folks have better luck with the front of the car on ramps or otherwise elevated when refilling. i have a flushing tee in the heater hose and leave the cap off until coolant is close to coming out.
 

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:biggrin: no obsessing ... but i do tow and wanted to be sure over 50% ... basically the decision is buy 1 gal of coolant or 2 gal. so, 1 gal is just fine.
 

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2019 Crosstrek 2018 XT
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:biggrin: no obsessing ... but i do tow and wanted to be sure over 50% ... basically the decision is buy 1 gal of coolant or 2 gal. so, 1 gal is just fine.
The difference between 30% and 50% is probably only about 5 degrees or so. No big deal.

But the higher concentration is probably easier on the WP seal.
 

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Discussion Starter · #9 ·
According to hayne's, it holds 9.8 quarts? Seems like a lot to me. Anybody know how much they really hold?
 

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According to hayne's, it holds 9.8 quarts? Seems like a lot to me. Anybody know how much they really hold?
I have an 06 non-turbo. I changed the coolant over the weekend. I think the owners manual stated the capacity was 7 quarts. I got about 6 out by removing the thermostat and emptying the coolant overflow tank.

I refilled it by first putting in the gallon of Subaru concentrated coolant in the radiator (plus a bit in the overflow tank), then topping up the radiator and tank with distilled water, running it for a while, letting it cool, then refilling the overflow tank. Seemed to work fine. During the cooling period, the system sucked up a lot of coolant from the overflow. I also put in a bottle of the Subaru conditioning stuff.
 

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Old thread I know, but for future searchers like me...

A higher concentration of coolant gives greater boil over protection, but not better cooling. Those running more than 50% coolant consider adding a water wetting agent, which allows for greater heat transfer to the liquid. Coolant is less efficient at transferring heat than is plain water. Hence why, for maximum cooling efficiency, like in a towing situation, you'd want to run closer to 30% and add a wetting agent. I've used Redline Water Wetter for a few years.
 

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Coolant is less efficient at transferring heat than is plain water. Hence why, for maximum cooling efficiency, like in a towing situation, you'd want to run closer to 30% and add a wetting agent. I've used Redline Water Wetter for a few years.
Well water has a higher heat capacity which on the surface of it seems like it would cool better. But remember ..heat that is picked up in the engine must also be rejected at the radiator. So water is quicker to pick up heat and slower to rejust it.

End result?? Your engine will heat up just a few micro seconds slower with water than antifreeze but at steady state there is no difference in the two (antifreeze vs water). Water wetter May help avoid hot spots by preventing nucleate boiling, but it won't keep the engine cooler at max thermostat opening. The only way to keep an engine cooler at at max coolant flow (stat open) is to have a bigger radiator.
 

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Physically that is not how heat transfer works. Quicker to pick up means also quicker to release. The _rate_ at which heat transfer occurs is the issue, and that rate governs both the heating and cooling of a fluid. Water also has a higher heat capacity.

Some interesting notes here...

Ethylene Glycol Heat-Transfer Fluid
 

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whats the difference

The difference between 30% and 50% is probably only about 5 degrees or so. No big deal.

But the higher concentration is probably easier on the WP seal.
what the difference , if 5 degrees or so is no big deal why are you worried about water's heat transference.
 

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one statement is there's no big deal and the other is micro seconds i ;m confused
If you do a computer model of water vs different concentrations of antifreeze you will find that at steady state the engine will run the same temperature. The difference will be that as it heats up the water (having larger heat capacity) will delay that process by a very minute amount.

But again the difference between boil over temps is controlled both by the fact that water boils at 245 F with a 15 psi cap and 265 with a 50% Antifreeze concentration and a pressure of 15 psi.
 
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