Coolant Analysis: Prestone in 2002 WRX

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500
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Vermont
Shortly before I sold my WRX I sent in a sample of coolant to be analyzed. At 15350 miles on the car and the factory fill coolant, I drained, flushed, and filled with a 50:50 mix of regular Prestone and distilled water, with a small container (maybe 12 oz.) of Prestone Rust Preventer. At 30569 miles on the car and 15117 miles on the Prestone, I drained, flushed, and refilled with Subaru coolant and water. This sample I am about to post is on the Prestone coolant.
code:
  
Sodium        2570
Phosphate     689
Molybdenum    39
Iron          2
Copper        6
Lead          0
Aluminum      36
Boron         373
Silicon       73
Silicates     0
Nitrates      817
Nitrites      674
Conductivity Meter (D-4308)
 Conductivity 3250 uS/cm
 TDS          944 mg/l

That is all that was listed as being analyzed, and there was the typical OAI/CTC comment "Test results performed indicate no corrective action required" I have no understanding of coolant analysis, so I am pretty dependent on their comment. As the car is sold, it is also pretty much irrelevant to me. The WRX has an aluminum block and heads, iron cylinder liners, and an oil:water oil cooler. The turbo is also water cooled.
 

MolaKule

Staff member
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21,866
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Iowegia - USA
Sodium 2570 This a sodium additive used as a corrosion inhibitor, metal deactiator, and alkaline buffer. Phosphate 689 Antiwear additive for water pump. Molybdenum 39 AW additive and antioxidant for coolant and water pump. Iron 2 Copper 6 Lead 0 Aluminum 36 From radiator and/or coolant passageways. Boron 373 Antiwear agent and secondary alkaline detergent to remove rust and scale. Silicon 73 Mainly Antifoamant. Silicates 0 Dust or dirt in solid form. Nitrates 817 Nitrites 674 Since no head gasket is perfect, NOx gasses from combustion process leaks into coolant. Conductivity Meter (D-4308) Type of meter to measure how much current can pass through coolant. Conductivity 3250 uS/cm A measure of how much current can pass through coolant and indicates how many metals are in coolant. Not much good unless virgin coolant has been measured. TDS 944 mg/l An alkalinity/acidity figure. Again not much good unless virgin sample has been tested. [ June 23, 2003, 05:21 PM: Message edited by: MolaKule ]
 

nicrfe1370

Thread starter
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500
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Vermont
Thanks MolaKule. Hopefully my posting this will encourage others to sample their coolant, so we can build a database like we have with the engine oils.
 
Messages
392
Location
Toronto, Canada
Hey, wait a minute! did prestone drastically change their coolant? How come no silicates? Please confirm this is regular green Prestone and not the long life stuff, please. If this is true, then regular Prestone is OK for Honda water pumps!!!!!!!
 

nicrfe1370

Thread starter
Messages
500
Location
Vermont
This is the stuff that comes in the yellow jug, and the coolant itself is the crazy neon-green/yellow/gold (I'm kind of colorblind, so bear with me on the color). I switched the coolant out "early" because I learned that Subaru recommends only their coolant, with no alternatives listed in the factory service manual. Their coolant is the dark god-knows-what-color that almost looks like motor oil.
 
Messages
392
Location
Toronto, Canada
Apparently, in 1995 Honda issued a bulletin warning that normal antifreeze generally sold in the US contained silicates that were rough enough to cause premature wear on the water pump. Based on this, it was generally recommended that one use only silicate free antifreeze for Hondas. Upon further reading, I found that asian origin antifreeze is generally a different composition compared to domestic like prestone. Some Honda owners noted that their long life product was silicate free. However, normal prestone looked as if it contained silicates and thus was not recommended for use on Hondas. Maybe Prestone did indeed change their formulation to be more universally compatible. My suspicion is that this silicate free issue also applies to all imports like Toyota, Subaru etc. With imports hitting record numbers in sales Prestone etc must respond with appropriate product. I guess they can't say directly they changed their formulation because the older one was not that good .
 
Messages
597
Location
Salisbury, MD
I too was surprised by the low silicates and high phosphate in the Prestone. General internet rumblings indicate that Japanese car water pump seals hate high silicates and love phosphate, American car water pump seals seemed to do OK with high silicates and German car water pump seals hate high phosphate levels. I ran 40k miles with Prestone in my Maxima before switching to Nissan coolant, but hopefully, did no harm based on the revised Prestone formulation. That Maxima water pump is a bear to get to what with having to pull the engine and the timing chain cover.
 
Messages
392
Location
Toronto, Canada
that isn't too bad with the maxima. hondas are reputed to have had seized water pumps throw out the timing belt and destroy the valves!!!!! yikes. i'm packing prestone last winter in my legend and did this before becoming aware of the silicate issue. with this analysis i can sleep at night. thanks a million!!!!
 
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4,478
Location
Southern California
A month or so ago I was looking at Wally*World's house brand antifreeze/coolant and noted there was no mention of either silicates or phosphates. Upon checking a nearby Prestone jug, same thing. When I got home I did a little online investigating and determined that Wally*World's coolant is supplied by First Brands - the owner of the "Prestone" name rights. I contacted Prestone by email and received a reply the next day that confirmed their standard Prestone product is still formulated with silicates and phosphates, and that if my vehicle* requires a coolant free of those elements, I should use their long-life "Dex-Kool" compatible product. *A 2003 Hyundai Sonata V6 (aluminum block and heads). Hyundai's recommendation is a model of non-information stating only only to use "a quality antifreeze/coolant formulated for use with aluminum cooling systems". The slop the car came with is green/yellow, but I have read other posts in this section earlier that at least some Asian car manufacturer's coolant of that color are either reduced in or totally free of phosphates and silicates. I figure I'll leave it in for 12 months and then drain and flush with non-ionized water until it runs clear. I plan to refill with Havoline "Dex-Kool" and non-ionized water. And hope.
 
Messages
392
Location
Toronto, Canada
Here was Prestone's reply. Thanks very much for your inquiry. We have never determined that use of silicates in an antifreeze will lead to premature water pump damage. We do offer a silicate free formula called Prestone Extended Life Antifreze (stock # AF-888). This product should be located at retailers like Advance Auto, AutoZone, CSK, Murrays and Wal-Mart OK now I am getting worried. Is the lab's analysis right? or is the lab analysis wrong? In my reply they mention the extended life which is not yellow. So what's going on?
 
Messages
392
Location
Toronto, Canada
Hey molakule, you mention silicate as "dust or dirt in solid form" maybe you overlooked something? or is the lab looking for something else? maybe you can help us out on this dilemna?
 
Messages
392
Location
Toronto, Canada
From Prestone again: Thanks very much for your inquiry. The Prestone Antifreeze in the yellow jug contains a patented silicate technology. The Prestone Extended Life Antifreeze in the silver jug does not contain silicates. Either blend should be available at retailers like Advance Auto, AutoZone, CSK, Murrays and Wal-Martrs So why did the lab say silicates =0 Are the labs to be trusted???? Really intriguing.
 

nicrfe1370

Thread starter
Messages
500
Location
Vermont
This is really bizarre. The two possibilities are 1) I wasn't really using regular Prestone from the yellow jug, or 2) the lab totally screwed up. I just called the lab (it was CTC directly that did the testing, I didn't go through OAI) and they are going to get back to me. [ June 27, 2003, 04:29 PM: Message edited by: nicrfe1370 ]
 

nicrfe1370

Thread starter
Messages
500
Location
Vermont
Even though my coolant analysis report clearly displays Silicates at 0 PPM, the lab just told me that they do not test for silicates. I didn't ask why they would list it, but that seems to be a really dangerous practice. At least we have sort of answered that question.
 

MolaKule

Staff member
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Location
Iowegia - USA
A silicate MAY be an additive, which is a salt of silicon, oxygen, and a metal, or it may simply be the result of neutralized acid mixed with a metal. With the new sodium mercapto type additives (anticorrosion/base buffer), silicates may not be needed.
 
Messages
392
Location
Toronto, Canada
thanks for the followup. The Prestone I have in my engine is coming out this summer or maybe next year when I get my timing belt and water pump changed. As for the labs, that practice of listing but not testing is a definite NO NO. That is simply bad professional practice and no excuses accepted. I sound strong here but a lab is supposed to be totally analytical and whatever results that are listed are supposed to be verifiable. Off topic here, but Honda recommended that the water pump be changed every 90k with the timing belt interval. That was in 1990 before they started advocating the lower wear with the non silicate formula. I wonder if that means that the water pump will last two timing belt intervals with the non silicate formula???? hmm... If it doesn't then who cares????? The water pump would last for one timing belt interval anyways? Been though that twice with no problems.
 
Messages
597
Location
Salisbury, MD
I figure I'll leave it in for 12 months and then drain and flush with non-ionized water until it runs clear. I plan to refill with Havoline "Dex-Kool" and non-ionized water. And hope. Switchover from regular anti-freeze to Dex-Cool, even with a thorough flush, is not normally recommended. Rather, stick with what the car was designed for. Coolants with large doses of silicates for Japanese water pumps is a no-no, phosphates are used in its place. Buy either some Nissan coolant or Honda coolant. It's the dark green stuff you see in all Japanese cars. I'm clueless on the Hyundai's. [ June 28, 2003, 05:42 AM: Message edited by: ex_MGB ]
 
Messages
392
Location
Toronto, Canada
I've been using Prestone for the last 12 years in my japanese car. The last water pump was changed about 60K miles ago at the same time as the timing belt. What I'm thinking now, is could the silicates have built up a false seal and if I switchover, it starts to weep? Like oil issues?
 

CJH

Messages
489
Location
Pennsylvania
quote:
Some Honda owners noted that their long life product was silicate free. [/QB]
Honda's product is silicate free, but is NOT LONG LIFE. In my 2000 Civic Si, they recommend changing it at 35,000 mile intervals. Compare this to my GM cars where they recommend DexCool be changed at 150,000 miles or 5 years. The silicates are similar to sand. They are in the antifreeze to "sand blast" the cooling system internals and prevent corrosion. On Hondas, the water pump seals are damaged by the silicates. Honda water pumps can last indefinitely if run on silicate free antifreeze.
 

CJH

Messages
489
Location
Pennsylvania
quote:
Originally posted by ex_MGB: I figure I'll leave it in for 12 months and then drain and flush with non-ionized water until it runs clear. I plan to refill with Havoline "Dex-Kool" and non-ionized water. And hope.
You would have to have rocks in your head to switch to Dex Cool I had 2 cars with Dex Cool and one of them I converted to traditional green coolant. The Dex Cool is highly corrosive to gasket life and is prone to gelling if air gets into the cooling system. I saw a link to a page where someone is preparing a class action suit against GM for using this stuff. I would avoid it. Just my two cents.
 
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