coolant flush yay or nay

[Dupree]

Ok here is the deal, I have a buddy with a 2005 outback H6 similar to mine, his has 130,000 but he has been a naughty boy... he has not ever changed the antifreeze. It is factory fill. there is some brown sludge apparent in the cap and looking down in the radiator, it still has green fluid but is obviously well spent.
I have never done flushes because I believe in maintenance and get my fluid changed enough its never been sludge like that If ive ever felt necessary to flush i run a distilled run through, but I fear this wont be enough so what flush do you all recommend. I was looking to the schaeffers but they say not to be used with OAT antifreeze which is precisely what is in his vehicle....so any adice would be greatly appreciated

 

[SHOZ]

I use a citric acid flush. Drain and fill with distilled and the flush. Drive for a couple hours. Drain and refill with distilled. Drain and refill with 70% (cause you will not get all the water out). top off with 50% after the system cools down.

 

[Dupree]

I ran over to his house and took some pictures to show you.....what citric acid flush did you use

 

[SHOZ]

Just some auto parts generic cleaner. Read the ingredients. And when filling with the 70% that is one gallon. Rest is 50/50.

 

[Sayjac]

Looking at the cap and housing and 130k miles on current, I vote yay to the flush first. Prestone Flush is a readily available citric acid flush and depending on how long you choose to use it (keep it in the system) determines amount of cleaning. Then as noted, do some distilled water radiator d&f's till clear or close.

As for antifreeze, two suggestions and both would be in concentrate. That way all you have to do is add half system capacity with AF to rad and top with distilled water.

No particular order. Peak Global Lifetime concentrate a good choice and what I'm running in my Tacoma. Does not contain 2eha (which doesn't agree with some gasket and seal materials), and can be found at some Napas or can sometimes be ordered. Long Life Life service interval too.

Second, PepBoys OEM brand Asian PHOAT AF, comes in a concentrate. Pick what tint/color you desire, same otherwise. Also a long/extended service interval AF. https://www.pepboys.com/product/details/879925/00454 . A bit more expensive than PGL, but PGL sometimes hard to find in full strength.

Either AF should serve you well and concentrate especially good for a complete flush.

 

[Oro_O]

The standard recipe is about 1lb citric acid/1 gallon dH20. You can get the stuff cheaply at home brew suppliers, other places like that. You will need ~2lbs. Dissolved in hot dH20 before you pour it in.

I would do a straight tap water flush first to get rid of as much particulate as I could before I added the CA mix. Sort of like pre-rinsing the dinner dishes. This will let the CA mix be more effective on its cycle. I would do TWO dH20 cycles after the CA mix to get it down to a very low level - remember you can't drain out the heater core.

I don't think this engine has block drains but you can pull the thermostat to help get more drain each time. Don't forget to bleed the air out correctly when you do the final fill. On the final fill, I add straight concentrate coolant, 60% of total system volume (find that spec on a Subaru forum/from the manual). Then top up with dH20. This was I know I am at 60% coolant and don't have to worry about water trapped in heater core. Cycle, bleed, top-up, then fill overflow container.

PS- when bleeding, it REALLY helps to have the car nosed up-hill or on ramps if you are in a desert.

Really helps get the air out of traps and up to the top to vent.

 

[Dupree]

I will be using Subaru Long Life coolant, trying to decide on hoses, they all look good none are spongy all looking solid, but they have been in there for a while so idk

 

[Dupree]

I am thinking of doing the Kool it radiator flush, and I might use the pentosin a2 OAT coolant in leu of the subaru stuff I can get it overnight special ordered from napa

 

[Olas]

In that condition I'd drain & fill with plain water two or three times, then onto citric acid, back to plain water two or three more times.
Remove and back flush the radiator then fill her up and youre good to go

 

[Brian Barnhart]

I no longer do chemical flushes. Twice (out of 2 times) I had to replace water pumps very soon after strong flushes so I stopped doing them. Now I just use distilled water and have had no more issues.

Therefore, if it were me, I would do one or perhaps more water flushes. Drain, refill with water and run at idle long enough to reach operating temp. Drain, and perhaps repeat once or twice more depending on how the first flush looks. Then add water and the coolant of choice to achieve a 50/50 dilution.

This goes double if it's someone else's car. In fact, I don't even like addressing cooling system neglect on other people's cars.

 

[Kira]

Hello, I'd use Subaru coolant because "everyone" says to.
Your hoses are 10 years old and look good? Ask at their used car department and see what they say.
Get it clean and fill it with the right stuff.

If there's a "foolproof" coolant I go for it. Subarus are finicky so don't monkey around.
I've given up asking about hoses. I've asked here, at dealerships, on my cars' specific boards. NOBODY will even offer a guess on hose longevity.

I'll be changing my Volvo's hoses in a few weeks. They're 15 years old and "look OK". I did my sister's Jeep's ('99 XJ) at 13 years of age and when I was done the new hoses looked so good in the engine bay and the old ones on the ground (in clearer light) looked old and crispy.

You're at 10....wanna go for 12?....15?

 

[440Magnum]

Here's another vote against an acid flush. I'd do a couple of water flushes, refill with 50/50, and then probably do another dump/fill in about a year. Kinda like with crankcase deposits- sloooowly letting pure water and new coolant take all that precipitate back into solution over time.

 

[69GTX]

Originally Posted By: 440Magnum
Here's another vote against an acid flush. I'd do a couple of water flushes, refill with 50/50, and then probably do another dump/fill in about a year. Kinda like with crankcase deposits- sloooowly letting pure water and new coolant take all that precipitate back into solution over time.



That sounds good to me too.

I'm surprised that the coolant still has a bright green hue to it. I sort of expected a brownish look to it after 10 yrs and 130K miles. It might not be as bad as you think. Having deposits plate out in an air gap under the radiator cap may not be indicative of your entire system.

 

[Donald]

just flush it with tap water and if its clean, then drain and fill with distilled, then finally with coolant and distilled.

If its not clean after the tap water flush, then consider citric acid.

 

[Sayjac]

Guess I misunderstood about looking for suggestions on AF, coming right after Shaeffers AF but "they" say not to use OAT comment, and then advice desired at end. So forget the suggestions.

Will say though, if you're using the concentrated Long Life Subaru AF, that is the older PHOAT tech with the shorter service interval, recommended 2years/30k miles. The newer Subaru Super Long Life premix is the newer PHOAT with longer service interval, 5 year/50k miles. And doubtful anything mysterious about Subaru AFs, both are Asian PHOAT. That's it.

As for everyone using Subaru AF, I only looked at two google searches on Subaru sites regarding AF preferences and Peak Global Lifetime concentrate mentioned as used by several members.

Anyway good luck with your service.

 

[barkingspider]

Originally Posted By: Donald
just flush it with tap water and if its clean, then drain and fill with distilled, then finally with coolant and distilled.

If its not clean after the tap water flush, then consider citric acid.


^ This.

 

[Charlie2015]

No good deed goes unpunished. Drain and replace the coolant in order to stop further corrosion. Just remember if you flush it, the corrosion is all throughout the system. It will be impossible to remove all of it, and any problems that may happen in the future may be blamed on you since you last touched it.

 

[SavagePatch]

Will be adding Subaru Coolant Conditioner with the new fill?

 

[Dupree]

It is my best friend, the car could light on fire and explode and he wouldn't point the finger at me. we have been close friends for 20 years. I PH tested the coolant last night and get a 7.3 ph so it doesn't seem fully spent. I am planning the flush still (Lubegard flush) and 4 cleansing flushes with distilled water, Afterwards it will be refilled with Subaru super blue antifreeze (super long life since he likes to push his maintenance). I am planning on adding a bottle of the Subaru coolant conditioner

 

[prs]

Do not fear the "acid" of citric or phosphoric acid commercial flush agents. They do no harm to brass, copper, or aluminum. The green dye survives but the coolant has long been degraded.

Get a flushing fixture to fit the radiator neck to allow forced water flush. Remove thermostat (get a new thermostat and cap), Run tap water into the fixture with the radiator drain cock open or return hose loose and COOL engine idling to circulate. The old coolant and a little of the crud will exit as you flush. Do not get engine HOT, cold water/hot engine is bad juju. Turn engine off if it is getting warm. Remove fixture, close drain and add Prestone Super Flush and enough distilled water to fill and burp. Cap the radiator and go for a drive to get to operational temp.

Now drain that with care not to get burned. Let system COOL. Repeat the forced water flush with the cap fixture until drain water is clear. A fill with distilled and drive before draining will assure all your new fill is not contaminated by the tap water. Hew thermostat and new Asian type coolant mix, color does not matter. New cap. Clean and add coolant to recovery tank too.

Water pump failure after flush agent means the crud was not flushed out after the agent loosened the crud or agent was not exposed to crud enough. Or, pump was already ruined by the neglected system.

A lot of trouble to do, right? "Best defense is no be there?" Regular on schedule changes with proper fluid and distilled water should let us avoid all of that hassle.

prs