Coolant type for 2004 WRX?

My concern with that is that it contains a small level of silicates. I know people have beenb using silicated yellow Prestone for years, but I still get the feeling that silicated coolants and small Japanese radiators don't mix.

I'm thinking of just going to a dealer that sells the Subaru green stuff. I was curious as to what others have tried. I understand that most (before extended-life coolants) Japanese car radiators are designed with silicate-free, but high-phosphate coolant in mind. Phosphates are supposed to be fine corrosion inhibitors, but the apparent problem is that they'll form precipitates in hard water. I always use distilled water.

Hi,

I think you've hit on it right there!

For the first few years of my driving career, I bought into all this "my coolant's better than your coolant" stuff. Then an old time radiator guy got a hold of me about 35 yrs ago and told me, "Son, get regular green Prestone, mix it 50-50 with DISTILLED water (his emphasis), and spend your time driving the car instead of worrying." So far, his advice still holds IME, with no coolant related problems using it in several Japanese, as well as German, English, Italian and American makes.

That's not to say there's nothing to this different coolant thing, though. I've had two problems directly coolant related over the years. First was 30+ yrs ago when DuPont came out with a leak-sealing recipe for their Zerex coolant (ok, so I just can't resist trying something new in the lotions and potions dept.) That clogged both a radiator and a heater core. It was taken off the market quickly in response to lawsuits.

The second was when I tried Havoline's Dex-cool formulation (orange) in my Subie, which has a ton of miles and always "weeped" at the head gaskets. It actually started leaking enough to leave a spot on the floor. Switching back to green eliminated the problem.

As for the extended life stuff, I'm "conflicted." Go over to most any Toyota group and they rant and rave about Toyota's "special" red coolant (just short of the religious fervor Honda guys sometimes exhibit!) My Camry's been maintained exclusively by the dealer prior to becoming mine, and it's had green Prestone in it as long as I've known of the car (several years before I got it), changed once a year, about every 20k miles. It's got almost 227k miles on it today, with no coolant related problems I'm aware of. And I'd bet my quarter the dealer didn't even use distilled water, either!

Best of luck with your particular choice!

Rick

I'm still wary about using regular Prestone. I recall it was from one of their FAQs that I found out the reason why phosphates aren't recommended by European automakers. European countries typically use hard water from wells. Past a certain threshold of hardness, the mixture will form precipitates. You'll have junk floating around in the cooling system, and you've instantly depleted a good amount of your corrosion inhibitors.

As far as Prestone goes, they haven't exactly kept the same formula over several years and different ownerships (Union Carbide, First Brands, and now Clorox). They probably hadn't developed silicates when you first started using it. They've actually included organic acid corrosion inhibitors for about 20 years. I'm not even sure what's in their "mix with any color coolant" stuff they're marketing now. I'm getting the suspicion that this is very different than anything they've made in the past.

The thing about the Japanese carmakers that spec their own coolants is that they insist on phosphates - even in their extended life coolants. There's really nothing wrong with Phosphates, but Prestone/Havoline/GM/etc seemed to have taken out phosphates from the Dex-Cool formula(s) in order to make it some sort of "universal" coolant for any number of different carmakers.

OK, do what I do. Look in the owner's manual and match the specs down at the Auto Zone. If the manual says 5W30, API SL, then I get an oil that has that spec. For coolant, if it says Prestone Orange with Berry flavoring, I go to the Auto Zone and check labels on the coolants until I find the one I want. Simple. Hasn't failed me yet thru 25 years of car ownership.

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My manual says use "Genuine SUBARU coolant or an equivalent". I realize that it may not be catastropic to use something different, but I can't for the life of me figure out what's an "equivalent".

I can figure out what an "equivalent" Dex-Cool or G05 coolant is. I'm guessing it's a Japanese carmakers' silicate-free and borate-free non-extended-life coolant.

I've read the same thing. Which is why so many people recommend DISTILLED water! The Europeans have made many advances in the automotive world ahead of the rest of us, but to go thru all the song and dance of redesigning the chemistry of coolants to work with cruddy water instead of just spec'ing distilled water strikes me as being particularly Teutonic: "Well, if it will work well with just four bolts, let's see if we can make one with 20! And we'll call that superior engineering, even if it doesn't work as well." (A two sentence case study of the demise of VW, at least in the US?) I have a hard time believing they don't have distilled water in Europe...

What's an "equivalent" to Subaru's coolant? As kind of a corollary to what Ragnar says, I figure you can use anything the factory doesn't PROHIBIT (as is the case with some diesel mfrs!) Even Honda doesn't say you HAVE to use their coolant, they just warn you MAY not get as good service from others (at least that's what the g/f's Civic's manual says.) Besides, how many antifreeze factories does the world have and where does one think the auto mfrs get their supplies? Methinks there's a lot more advertising hype than science involved in much of this stuff. The fact the dealer maintained my Camry w/ Prestone out in the shop, while inside the parts dept sold the "Genuine Toyota" juice, and considering the service the car's given its previous owner and myself, speaks volumes to me. As does personal experience with many, many other cars. OTOH, maybe I've just been lucky?

Rick

AWEsome. :-)

Here's a link to a relevant thread on NASIOC-

I'm using the Peak Global coolant, silicate and phosphate free. Comes in a handy 50-50 premix so no need to add distilled water, just pour it in. The new universal Prestone should be ok as well, I think it's also available in premix form. Dexcool is a GM formulation and should NOT be used in any vehicle that did not originally come with it. It cannot be mixed with other coolants.

practically

Prestone has made claims that they've lab tested their Extended- Life Dex-Cool coolant to be compatible with various extended- life factory coolants. I take that with a grain of salt.

However - there's absolutely nothing wrong with phosphates provided hard water isn't used. The problem with silicates in any application is that they will come out of suspension. That may not be as big a deal in large American make radiators. If one uses coolant with silicates, it may be a good idea to refill (and perhaps flush) every year to get out the old stuff before it plugs up anything. Borates are abrasive.

Also - the owner's manual instructions say nothing about pulling the engine block drain bolt. I know there's got to be one, since that's where the factory engine block heater would go. Anyone know where to find it, and if it's easy to reach? I'm not doing the job any time soon, but I'd like to know as a reference for the future.

I was digging around for any info, and I came across this for a

2005 MY Legacy/Outback:

This appears to be for dealer maintenance, but they recommend the use of an evacuation/refill tool to speed up the process and eliminate air pockets. It also recommends Subaru coolant, although I know that some dealers just use whatever they feel like. I looked up one of these tools, which requires access to shop air pressure to create the vacuum.

I've read some posts indicating that people here have "burped" their cooling systems by letting it cycle with the rad cap opened. My last car had an air bleed bolt near the thermostat housing. Of course I could just let it stay and the air will eventually be evacuate via the overflow tank (but how long would that take?).