OK, in my meanderings around with my HG issue on my '97 Legacy, I've discovered that it was running DexCool coolant. You know that hi-dollar orange coolant. Is this what's SUPPOSED to be in these engines? I bought this car from a branch of a local GM dealer, who serviced it before putting it on the lot.

Did they just put that in because they had it on hand?

No, you should not be running GM dexcool or any OAT coolant (i.e. all makes/all models) coolants in a soob. You MAY be able to run those succesfully provided the system was flushed well with distilled or RO water before the switch, the coolant level is checked regularly by removing the rad cap (not just looking in the overflow tank), and there are no leaks sucking air into the system.

 

There are articles on http://www.endwrench.com

 

The fact that Subaru does not seem to want dexcool run, and GM used to own part of Subaru....well I wouldn't run it..though I have with no ill issues in the past.

 

It's the glopping issue. If air is in the system corrosion can occur on the aluminum parts in a soob...then coolant washes over it...and then glopping ocurs. This has occured in other vehicles too.

Ok then good ol' Ethelyne Glycol will be put back in when I get the HG's fixed.

 

Thanks for the good info.

Ok. Ethylene glycol is not sufficent. Most coolants are about 96% ethylene glycol and/or polypropylene glycol. Plus 1-2% water. The remaining couple percent are the additives. Run either genuine Subaru coolant, or check the ingredients to find something at least similar and that is not an OAT. BASF G-05 formulation to me seems at least similar.

Thanks. Should I get the HG leak additive when I put it back together?

 

The Subaru cocktail that is.

I don't think the Subaru coolant conditioner (relabelled Holts radweld from the U.K.) can really do anything for the 2.5L phase I dohc exhaust blowing into coolant leak. It may help the phase II peeping leak or any hose connection leaks. However I believe Subaru has said retrospectively to use the coolant conditioner in all soobs, and adds the coolant conditioner to all new soobs at the factory.

 

Ok, I was thinking it would be some added insurance against another $400 repair.

Oh yes, also be sure to use distilled or deionized water with the coolant if it needs diluting. It costs like 99c a gallon and doesn't have the chlorine and other ions associated with tap or softened or well water.

I always keep bottled (distilled) water around for coolant & lead/acid batteries

I was formerly a GM dealer tech for 10 years. I would not put dexcool in ANYTHING ever! I've seen the problems this stuff causes.

I was a tech at a Ford dealer for a couple years, until I learned that I REALLY don't like working on other people's cars for a living!

dexcool... bad stuff. f'd up my 96 chevy p/u..headgaskets went due to it. pure garbage.

 

http://www.consumeraffairs.com/automotive/gm_dexcool.html

Well, finding (and paying for!) genuine Subaru coolant could be a problem.

 

To flush:

 

I would recommend a full drain, fill up with pure water (destilled, milli-Q, whatever, just not tap water), leave engine on with rad cap off to expell air, when the rad fan comes on, install the rad cap. Drive...enjoy life behind the wheel of a Subaru.

 

Come home, drain again and fill with any good "regular" coolant. Most of these are green or blue. Avoid red or orange.

 

 

Having said that, the Motul "Expert" coolant I am running is yellow, but it's the same ingredients as the blue stuff - only a lower concentration. And it's meant for bikes. The only real difference is a higher freezing point. This coolant is very good though, excellent heat transfer.

You can go read the Cooling System FAQ in the Service & Maintenance section at NASIOC if you'd like. There's a link to a Subaru publication there which specifies that you must use a phosphate-additized coolant for proper protection of the aluminum. It makes no mention of silicates whatsoever. Unfortunately, the thread in that FAQ almost immediately says you should use a non-phosphate, silicate-free coolant.

 

Bottom line: Subaru's specification of a phosphate-additized coolant and no mention of silicates means they are specifying the use of good old-fashioned anti-freeze. None of the newer, fancy, extended-life or lifetime crap. Use the plainest, most traditional stuff (if you don't use their branded stuff) and change it out every couple or three years is what Subaru says to do.

Yes Subaru does specify a phosphate antifreeze. But by their own admission their coolant does not contain phosphate but rather uses 'a trick of chemistry' I believe they say.

 

No mention of silicates, and no listing of a silicate i.e. sodium silicate or 'sodium salt' on the ingredients list would be reasonable to think it is a non-silicate coolant.

 

The ingredients you do NOT want to see are 2-Ethyl Hexanoic Acid or Neodacanoic Acid, these are typically in OAT coolants such as dexcool.

I punted and bought Subaru brand coolant from the dealer.

I punted and bought Subaru brand coolant from the dealer.

hehe...ok sure take all the fun out of it!

Yes Subaru does specify a phosphate antifreeze. But by their own admission their coolant does not contain phosphate but rather uses 'a trick of chemistry' I believe they say.

 

No mention of silicates, and no listing of a silicate i.e. sodium silicate or 'sodium salt' on the ingredients list would be reasonable to think it is a non-silicate coolant.

 

The ingredients you do NOT want to see are 2-Ethyl Hexanoic Acid or Neodacanoic Acid, these are typically in OAT coolants such as dexcool.

 

I agree that Subaru's coolant is pretty much a Peak long-life coolant, probably phosphate-free and probably silicate-free. My point is that they say to use that which is the most 'conventional' or old-school antifreeze there is in the absence of their own branded product being used. The presence of these things does not cause any difficulties, IMO, it just means you have to change the coolant out more frequently. I agree that the OAT could be an issue.