Coolant

Hi,

I don't know about an "official" position, but my "unofficial" position is to stick with the color that came from the factory. I've experienced some leakage changing to orange from green in older vehicles that went away when I went back to green. I understand there's been documentation of some kind of sludge formed if the two are mixed. Some have reported no problems. YMMV.

Rick

My new GM has Dex-cool of course. Lots of discussion on other NG's about this re: AKA Death-Cool. Supposedly there is a lawsuit against GM for leaking intake manifold gaskets caused by Dex-Cool. It's also rumored to cause sludge buildup in the cooling system. Yes, you need a complete flush if changing between the two. I've also heard that Dex-Cool is not to be used in brass radiators. I'll stick to non-sylicate green stuff in the Subie & probably switch over when the warranty runs out on the GM. My $.02 FWIW.

Mike '01 OBW

Well, I would be the idiot that tried to switch from green to orange on my

2002 subaru. Prestone says you can....BUT DO NOT BELIEVE THEM. There was a bit too much corrosion in the system after 6 months and 6,000 miles. The corrosion floats to the top and I noticed a color change in the coolant overflow bottle. I got to the shop and used a super flush on it four times then added the Prestone Green coolant. Hopefully this will stop the problem. It looked like I took the radiator to the beach.

Debating if I should add the subaru conditioner to it or not...any ideas? Matt

Thanks for all the comments.

Mickey

I let my dealer put in their recommended cooling system conditioner about

GO GREEN! See my message below.

Matt

Previous message-Well, I would be the idiot that tried to switch from green to orange on my

2002 subaru. Prestone says you can....BUT DO NOT BELIEVE THEM. There was a bit too much corrosion in the system after 6 months and 6,000 miles. The corrosion floats to the top and I noticed a color change in the coolant overflow bottle. I got to the shop and used a super flush on it four times then added the Prestone Green coolant. Hopefully this will stop the problem. It looked like I took the radiator to the beach. Matt

I'd get rid of as much green Prestone (from the yellow bottle) as I could. I've heard the amount of silicates in regular Prestone has gone down over the year, but it still has it. Silicates are known to cause a host of problems when they inevitably go out of suspension.

Most Japanese carmakers use smallish radiators with smaller passages. The word I hear is that silicate sludge buildup can become a bigger problem in such radiators.

My theory is that perhaps Dex-Cool may not be the best solution because Japanese carmakers prefer to use phosphate corrosion inhibitors in addition to some organic-acid inhbitors that most carmakers use. To follow most European carmakers recommendations for phosphate-free coolant, Dex-Cool was thusly formulated. The idea is that typically hard European water causes abrasive precipitates to form. I'm guessing that a phosphate and OAT coolant (Japanese OEM) may be the correct one for most Subarus.

Hi,

Dumb question: how do silicates go out of suspension when they're in a constantly circulating base liquid?

There's a lot of argument pro and con on silicate presence or absence in coolant. I've run regular green Prestone in a variety of cars, always using a 50-50 mix of coolant and DISTILLED water. I'm not going to stick my neck out and say for sure there's been no problem, but I will say I haven't noticed one. This with American, English, German, Italian and Japanese cooling systems. They've all been changed at two year intervals. Water pumps have lasted from 125k miles to 150k+ miles, radiators haven't clogged or developed corrosion leaks, etc.

So I'll add another theory: perhaps the silicate "problem" may be one of those that only crops up in neglected systems?

Rick

They precipitate out. I would guess that hot/cold cycles would have something to do with it. I don't think it matters if it's constantly being mixed. Oil sludge can form in the crankcase even though it's constantly circulated. In addition, because of silicates, coolant has an 18 month shelf life. I could imagine coolant sitting in a warehouse and/or shelf that long.

I don't know of any Japanese carmaker that will use silicated coolant at the factory. Most warn not to. check out this service bulletin from a maker of heavy duty heat exchangers:

"1. ANTIFREEZE Antifreeze is high in silicates. High silicate antifreezes were designed to protect the aluminum components in automobile engines. More and more of this type of antifreeze ends up in heavy-duty engines where it can cause problems.

Silicate gel adheres to cold surfaces so it is seen in the radiator first. We suggest the contaminant be analyzed and the proper corrective action taken. We have seen instances where the problem is not only silicate but other contaminants as well."

At the very least, a little bit will precipitate out, bond to water pump seals, and be mildly abrasive.

Well, green IS my favorite color...

-Matt

IIRC, the problem comes when you switch from one format coolant to the other (and I can't remember which sequence is badder, or if both are equally bad)...it's difficult to get ALL the residual coolant out, and apparently they don't co-reside well.

I got enough info that I decided I'd stay with what was in there, and moved on to other matters. I think I saw it up on nasioc.com.

Steve

Zerex G-05 is supposedly a low-silicate organic-acid coolant. Most Japanese carmakers say silicates are a bad, bad thing - especially Honda and Toyota.

I thought water pump cavitations were more likely with borates.

Here's a pretty good explanation:

"In Europe the water is generally very hard with high concentrations of minerals. European car manufactures prefer coolants with little or no phosphates. The phosphates can react with the magnesium and calcium salts in hard water, which can form solids. These solids can wear erode seals or clog narrow cooling passages.

Japanese manufacturers prefer coolants that are free of silicates, but higher in phosphates. It's difficult for the owner of a Japanese import to find this kind of antifreeze at the local parts store or even the dealership. However, for years American shops have been installing the traditional green coolant in Japanese imports with no problems.

American and Japanese coolants contain phosphates to protect the iron and steel parts in the engine. Even though the U.S. has hard water, it is not nearly as hard as the tap water found in Europe. In Europe it is not a good idea to use the standard green coolant. In addition to phosphates, most domestic coolants contain silicone and silicates. The silicone helps lubricate the water pump while the silicates help protect aluminum parts by coating the surfaces."

This is what Prestone has to say

"Q: Does Prestone® Antifreeze/Coolant contain phosphates? A: Some European automobile manufacturers request that a phosphate-free antifreeze be used in their vehicles. This issue is related to the extremely high mineral content of the water in Europe. If you were to mix an antifreeze that contained phosphates with the type of water they have in Europe, it may produce deposits that can settle in the cooling system and promote corrosion."

Hi,

This has been my experience, but once again, it looks like the various sources cited mention the same problem: hard water. I mix my coolant with DISTILLED water ONLY based on advice from a mechanic/radiator guy over 30 years ago. The hard water problem's been known for a long time!

Another question: don't they have distilled water in Europe? Seems a far simpler solution than working the chemists overtime to come up with exotic formulations. Sounds like an outgrowth of the "myth" of German engineering at work: "Hmmm... we could build this with four bolts and use a regular wrench, so let's see if we can build it with 20 and have to invent two new special tools to reach and turn them. Then call it 'sophisticated engineering.' And when it fails because it's too complex to be reliable, blame the operator for not knowing how to use it properly."

Rick

Fine. As to any potential for silicates gelling out, I don't think hard water has anything to do with it. It also sounds like liquid silicone slows down the silicate-to-gel process. I've heard enough horror stories about silicate gelling to conclude that it's not worth using yellow-green Prestone in sub 2-gallon capacity Japanese radiator.

I brought a bottle of silicate-free coolant and a bottle of distilled water to a shadetree mechanic - with specific instructions to use the distilled water. When I got the car back, there was about a quart of coolant left in the bottle, but the distilled water was unopened. I guess regardless of what I asked for, he was going to use tap water.

I guess the Europeans are so used to their own rules - i.e. it's inevitable that someone is going to mix the coolant with hard well water. I used to live in Santa Clara, California, where 2/3 of the water was from wells within the city limits. I measured the mineral content with an aquarium test kit where the number of drops of a chemical was used. You keep adding the drops until the mixture changes color. I stopped adding them after a point where I knew it was way too hard. This is probably the kind of water European carmakers design for.

LoL on that one. It also hold true with Heckler & Koch weapons. They're good, but reinventing the wheel in a previously unimagined format seems to be an obsession.

Steve

"Special tools" are usually needed for anything built in imperial measurements. What's wrong with using the decimal system, lads?

Florian ;)

Yes...

H&K's always been way out of my price range (using the theory that even with unlimited amounts of money--not my problem!--there's a right price for everything, which they exceed!) so I'll take your word on their quality.

For an interesting aside on this obsession, see if you can find the story on the very first day of the Panzer field trials during WWII. The Germans were certain they had invented the ultimate tank, and were laughing themselves silly at the Russians building the T-34s which my forefathers thought would never run: those Russians aren't smart enough to build a tank, you know!

Comes Field Trial Day 1, and 246 Panzers were sent out in the morning for testing. At sundown, 64 were still running. The rest were broken down, and couldn't be fixed until technicians and parts were brought in from Berlin to try to get them going again, which was nigh on impossible under field conditions. (Sound familiar to any owners of current German cars? The more things change, the more they stay the same?)

You can go to accounts of the war on the Eastern Front to see how the T-34s fared!

Rick