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Changing coolant


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So my 09 legacy 2.5 currently has green coolant in it, not sure if it’s subaru coolant or not. I planned on changing it so today I bought blue subaru long life coolant to put in it. I also planned on running distilled water through it to get most of the old stuff out. How could I do this to get most of the old coolant out?

Also, should I use the subaru coolant conditioner? I didn’t buy it because I think it’s a scam. My head gaskets seem to be leaking a little bit and from what I’ve read adding the conditioner won’t help if they already started leaking. Thanks in advance

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I looked into this since no one has replied yet. Seems like pulling off the thermostat housing is the best way to drain the engine block. In the attached image, step 4 is just draining the coolant from the radiator, it doesn't say anything else.

 

Spill free funnel is also handy to have for burping the system

https://www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY

 

 

Also, I don't use coolant conditioner, I don't think our 09's need it. Our cars leak oil from the head gaskets, never heard of them failing and leaking coolant. Edit: After thinking about it a little more, I wonder if this is why subaru calls for shorter coolant change intervals after the first one, because they don't expect you to get all the old coolant out by draining the radiator.

thermostat.thumb.jpg.f368e175a82bd33a88777ff3373fbf0d.jpg

Edited by apexi
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I looked into this since no one has replied yet. Seems like pulling off the thermostat housing is the best way to drain the engine block. In the attached image, step 4 is just draining the coolant from the radiator, it doesn't say anything else.

 

Spill free funnel is also handy to have for burping the system

https://www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY

 

 

Also, I don't use coolant conditioner, I don't think our 09's need it. Our cars leak oil from the head gaskets, never heard of them failing and leaking coolant. Edit: After thinking about it a little more, I wonder if this is why subaru calls for shorter coolant change intervals after the first one, because they don't expect you to get all the old coolant out by draining the radiator.

 

If I didn’t pull off the thermostat do you think it would be fine because I have green coolant in it now and I’m putting in blue coolant? I don’t think it would be enough to make a difference but I have heard of people saying that green and blue coolant can’t be mixed.

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I am not sure if blue and green can be mixed. I use the peak long life (cheap at HF, and actually really good). Coolant should be changed on a time interval primarily rather than mileage (it is all about how the coolant's additives that prevent corrosion wear off)

 

If you are doing a flush and don't wish to remove the T-Stat (which is the easiest way, though get a new gasket for that), then the solution is dilution. Run the car a few cycles of straight water (di water from the store, not tap water).

 

1) drain old coolant at radiator + T-Stat hose

2)fill up with DI water

3) run the car for a little (like 10-20 min) to dilute the old coolant

4) repeat 1 through 3 a couple times until draining is nothing but water

5) final refill with new coolant

 

You can be fancy and add coolant flush half way through the water cycles

I also second the spill free funnel, super handy

Edited by jaylew

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The green and the blue coolant should not be mixed as they are different chemistries and are incompatible. As mentioned a flush after draining as much green out as possible with distilled water is probably enough to get almost all of the green coolant out. Keep in mind that once you drain the distilled water solution there will still be an amount of water in there and if you use a 50/50 pre-mixed blue P-HOAT coolant the end result will be a higher freeze temp due to the water that was still in there. IMO, the color of the P-HOAT fluid does not matter at all. Whatever wally mart has on sale is what I use.
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FWIW, since 2007 my wagon has been on Prestone or Peak Global coolant. I change them out when the timing belt is replaced.

 

You don't need anything more.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

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The green and the blue coolant should not be mixed as they are different chemistries and are incompatible. As mentioned a flush after draining as much green out as possible with distilled water is probably enough to get almost all of the green coolant out. Keep in mind that once you drain the distilled water solution there will still be an amount of water in there and if you use a 50/50 pre-mixed blue P-HOAT coolant the end result will be a higher freeze temp due to the water that was still in there. IMO, the color of the P-HOAT fluid does not matter at all. Whatever wally mart has on sale is what I use.

 

Do you think it would raise the freeze temp enough to make a difference even if I got most of the water out?

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Do you think it would raise the freeze temp enough to make a difference even if I got most of the water out?

 

 

I was enough worried about it that I disconnected one of the heater core hoses and blasted air through there to force any water back to the engine block so it could drain out as much as possible.

 

 

I don't disagree with Max - the green coolant works just fine too.

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