I've heard people talk about 'low silicate' antifreeze and 'high silicate' antifreeze. What's the purpose of this silicate, and how do the applications differ? I've been told that you generally run high silicate antifreeze in diesel engines and you generally run low silicate antifreeze in automotive applications. Does anyone know if this is true, and if so, why? Reason being I've got John Deere antifreeze in both my '85 ford truck (which I'm not concerned about for obvious reasons), and my wife's '94 chevy corsica. Will this cause any problems in my wife's car?
silicate in antifreeze?
- Thread starter iskerbibel
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I did a Google search for "silicate antifreeze" and there is as much written about that as there is on oil. I would look at what the vehicle manufacturer reccomends and go with that. Just as important is the use of distilled water in your cooling system along with the required antifreeze/coolant.
Honda anti-freeze is silicate free. Honda says the silicates are hard on aluminum engine parts.
I know a lot of mechanics i've talked to about this don't think it matters. My landlord had an Acura Integra that had a whole eaten into the engine from the anti-freeze. Don't ask me how just reporting.
I know a lot of mechanics i've talked to about this don't think it matters. My landlord had an Acura Integra that had a whole eaten into the engine from the anti-freeze. Don't ask me how just reporting.
Well in Diesels you will want silicates, what happens in most big diesels and alot in Ford diesels is that when the cylinder fires it expands, and when it contracts it leaves a air pocket around the cylinder, when this happens a piece of the cylinder flakes off, and you can get a pin hole in the cylinder over time.
Now the silicates will attach them self to the cylinder wall, and they will flake off instead of a piece of cylinder wall.
At lease this is what I have been taught.
CRW
Now the silicates will attach them self to the cylinder wall, and they will flake off instead of a piece of cylinder wall.
At lease this is what I have been taught.
CRW
The silicates are added to bond to aluminum parts, radiators, heads, etc. It's an icky yellow goop for corrosion protection. There are likely other chemicals that are more expensive that also protect aluminum, e.g. in that honda stuff. The problem is if you don't change your antifreeze every two years the silicates start to form "sand" that stays in suspension and grinds your water pump impeller down to nubs.
My old man boycotts prestone b/c he says the silicates are unstable, and I follow him, even though our "intel" is at least a decade old. I try to use Texaco or Peak for ethylene glycol based "green" A/F but am afraid I don't have too much science to back that up... But do change your AF every two years and even the worst product will do (sound familiar?)
My old man boycotts prestone b/c he says the silicates are unstable, and I follow him, even though our "intel" is at least a decade old. I try to use Texaco or Peak for ethylene glycol based "green" A/F but am afraid I don't have too much science to back that up... But do change your AF every two years and even the worst product will do (sound familiar?)
thanks that answered my question. I will stick with Ethylene Glycol with silicate antifreeze on my truck, with 61,000 miles on it, and change it every spring.
I would use the Valvoline Zerex G-05 coolant, low silicates and the same formula as the Mercedes coolant, but at a cheaper price.
Dave
Dave
Silicates act as a sealant. You may have heard of a chemical called "water glass". It is sodium silicate and has been used to preserve eggs. It forms a glass like coating that protects surfaces.
Glass after all is mde from sand which is silicon di-oxide. Prestone and othe high silicate formulations often will form a gel in the recovery bottle which actually doesn't hurt anything. Low silicate formulas like Peak or Zerex are said to not be as abrasive and are less damaging to water pumps. They use other corrosion inhibiting chemicals. Diesel formulations contain nitrates which aid in prevent cavitation corrosion. The vibration set up by diesel combustion can cause pockets of vaccuum in the cooling system which are quickly and violently refilled with coolant. This can be quite destructive if the coolant isn't formulated to handle this. Zerex G-05 is suitable for diesels as well as gas engines and is probably the best all around product that is readily available.
Glass after all is mde from sand which is silicon di-oxide. Prestone and othe high silicate formulations often will form a gel in the recovery bottle which actually doesn't hurt anything. Low silicate formulas like Peak or Zerex are said to not be as abrasive and are less damaging to water pumps. They use other corrosion inhibiting chemicals. Diesel formulations contain nitrates which aid in prevent cavitation corrosion. The vibration set up by diesel combustion can cause pockets of vaccuum in the cooling system which are quickly and violently refilled with coolant. This can be quite destructive if the coolant isn't formulated to handle this. Zerex G-05 is suitable for diesels as well as gas engines and is probably the best all around product that is readily available.
zerrex sez its a "hybrid OAT" - what is that.?
If OAT = dexcool , then it seems people would want to avoid it??
If OAT = dexcool , then it seems people would want to avoid it??
also interesting
http://silverstone.fortunecity.com/ferrari/464/coolant.htm
http://silverstone.fortunecity.com/ferrari/464/coolant.htm
zerrex sez its a "hybrid OAT" - what is that.?
If OAT = dexcool , then it seems people would want to avoid it??
It means that their chemists have found a way to combine silicates with the Organic Acid Technology to take advantage of the characteristics of both.
Zerex G-05 is still low silicate, not a no silicate like Dex-cool.
If you change your coolant regularly (2 years or less) , it makes no difference what you use.
Not all dex cool equivalents are the same but they all will last longer than plain old green stuff. The problems reported with dex-cool can be avoided by simply keeping an eye on the cooling system. Most horror stories can be traced to people who don't know that there car hoods even open.
Zerex G-05 seems to be the closest to being the best universal anti-freeze. It is interesting to note,however, that Zerex conventional anti-freeze is advertised as having the same longevity as the supposedly better G-05. 5 years or 100,000 miles. Makes you wonder!
Ed
If OAT = dexcool , then it seems people would want to avoid it??
It means that their chemists have found a way to combine silicates with the Organic Acid Technology to take advantage of the characteristics of both.
Zerex G-05 is still low silicate, not a no silicate like Dex-cool.
If you change your coolant regularly (2 years or less) , it makes no difference what you use.
Not all dex cool equivalents are the same but they all will last longer than plain old green stuff. The problems reported with dex-cool can be avoided by simply keeping an eye on the cooling system. Most horror stories can be traced to people who don't know that there car hoods even open.
Zerex G-05 seems to be the closest to being the best universal anti-freeze. It is interesting to note,however, that Zerex conventional anti-freeze is advertised as having the same longevity as the supposedly better G-05. 5 years or 100,000 miles. Makes you wonder!
Ed
From Honda-
"Honda Genuine Antifreeze/Coolant
Most other coolants contain borates and/or silicates which can act as abrasives in your Honda's cooling system. Honda Genuine Antifreeze/Coolant Type 2 features extended protection for up to 5 years or 60,000 miles - making it the only recommended coolant for your Honda."
"Honda Genuine Antifreeze/Coolant
Most other coolants contain borates and/or silicates which can act as abrasives in your Honda's cooling system. Honda Genuine Antifreeze/Coolant Type 2 features extended protection for up to 5 years or 60,000 miles - making it the only recommended coolant for your Honda."
to the original thread, and to correct some misinformation that was stated: DO NOT use high-silicate coolant in a diesel. Is your '85 truck a diesel?
Older diesels like the 80's and early 90's Ford 6.9/7.3L IDI (indirect injection) and powerstroke (direct injection) diesels were most prone to cavitation. The definition of cavitation was well described above. This was combatted with an SCA- supplemental coolant additive. A google search on SCA will give good info on coolant in general. The SCA for Ford/Navistar was a combination of nitrite/molybdate by Fleetguard, with the molybdate more intended for cavitation protection. Nitrite I think is more for pH control, but don't quote me on that. Problem with adding this formula of SCA is that it had to go into low-silicate ethylene glycol (green antifreeze) at somewhat precise amounts otherwise it would make the silicate precipitate out of the glycol solution and form the green goo that was mentioned. For this SCA, you need a antifreeze that meets ASTM-4985 (I have it committed to memory). Another reason, if not mentioned, was you shouldn't exceed 70% of ethylene glycol to water mixture, otherwise as the ethylene glycol ages in the motor/radiator it will tend to drop out the silicate and form green goo and clog the cooling system.
From what I've learned, silicate is for aluminum protection/corrosion control and works by plating effect. But silicate has the drawback I mentioned, plus it is also inherently abrasive. This is one of the main reasons for the trend away from traditional green silicated ethylene glycol to the extended-life OAT (organic-acid tech) antifreezes, not to mention they have short service lives. If you are looking for low/no silicate ethylene glycol (green antifreeze) be cautious to what you pick up. If it says low-silicate but does not say "meets ASTM-4985", then it is not low silicate. Prestone in the yellow bottle is the biggest offender- it is by no means low silicate.
As for dexcool- there's a big myth (sort of) that dexcool is terrible because it sludges up. This story is part true and the way I heard it, came about when a good number of S-10 pickups left Chevy with coolant systems not completely/properly filled. They had air in them, and the dexcool after time would form brown clumps and result in cooling system failure. So in this case, putting the blame on dexcool would be like blaming some motor oil for engine failure when you only had 2 qts of oil in the engine when it calls for 5 (sorry, best analogy I can come up with). Point is, no cooling system should have air in it otherwise bad things are guaranteed to happen.
... '89 Ford F250 7.3L IDI diesel owner
some useful links:
http://www.imcool.com/articles/antifreeze-coolant/SCA-Part1.htm
http://www.intellidog.com/dieselmann/home.html
http://www.penray.com/coolingtechfacts/
http://www.dieselstop.com
http://www.amalgatech.com/technical/Index.htm
[ February 10, 2004, 02:25 PM: Message edited by: 1 FMF ]
Older diesels like the 80's and early 90's Ford 6.9/7.3L IDI (indirect injection) and powerstroke (direct injection) diesels were most prone to cavitation. The definition of cavitation was well described above. This was combatted with an SCA- supplemental coolant additive. A google search on SCA will give good info on coolant in general. The SCA for Ford/Navistar was a combination of nitrite/molybdate by Fleetguard, with the molybdate more intended for cavitation protection. Nitrite I think is more for pH control, but don't quote me on that. Problem with adding this formula of SCA is that it had to go into low-silicate ethylene glycol (green antifreeze) at somewhat precise amounts otherwise it would make the silicate precipitate out of the glycol solution and form the green goo that was mentioned. For this SCA, you need a antifreeze that meets ASTM-4985 (I have it committed to memory). Another reason, if not mentioned, was you shouldn't exceed 70% of ethylene glycol to water mixture, otherwise as the ethylene glycol ages in the motor/radiator it will tend to drop out the silicate and form green goo and clog the cooling system.
From what I've learned, silicate is for aluminum protection/corrosion control and works by plating effect. But silicate has the drawback I mentioned, plus it is also inherently abrasive. This is one of the main reasons for the trend away from traditional green silicated ethylene glycol to the extended-life OAT (organic-acid tech) antifreezes, not to mention they have short service lives. If you are looking for low/no silicate ethylene glycol (green antifreeze) be cautious to what you pick up. If it says low-silicate but does not say "meets ASTM-4985", then it is not low silicate. Prestone in the yellow bottle is the biggest offender- it is by no means low silicate.
As for dexcool- there's a big myth (sort of) that dexcool is terrible because it sludges up. This story is part true and the way I heard it, came about when a good number of S-10 pickups left Chevy with coolant systems not completely/properly filled. They had air in them, and the dexcool after time would form brown clumps and result in cooling system failure. So in this case, putting the blame on dexcool would be like blaming some motor oil for engine failure when you only had 2 qts of oil in the engine when it calls for 5 (sorry, best analogy I can come up with). Point is, no cooling system should have air in it otherwise bad things are guaranteed to happen.
... '89 Ford F250 7.3L IDI diesel owner
some useful links:
http://www.imcool.com/articles/antifreeze-coolant/SCA-Part1.htm
http://www.intellidog.com/dieselmann/home.html
http://www.penray.com/coolingtechfacts/
http://www.dieselstop.com
http://www.amalgatech.com/technical/Index.htm
[ February 10, 2004, 02:25 PM: Message edited by: 1 FMF ]
the coolant gets exposed to the air in the coolant recoverybottle in all the systems.
So what was different about the GM air problems?
So what was different about the GM air problems?
Wow! First you guys steer me away from Fram filters. Then away from Valvoline oils. And now, you are suggesting that Prestone is not the best antifreeze!!!!
Could someone summarize in some order the better antifreezes? Sounds like Zerex G 05 might be a winner.
How about generic, auto store stuff?
Or, someone suggested that if you change it on a regular basis (2 yrs.)it doesn't matter.
Thanks guys.
Could someone summarize in some order the better antifreezes? Sounds like Zerex G 05 might be a winner.
How about generic, auto store stuff?
Or, someone suggested that if you change it on a regular basis (2 yrs.)it doesn't matter.
Thanks guys.
prestone green is prob fine for the two vehicles you listed
The coolant in the recovery bottle is not under heat & pressure like it is within the motor and radiator. I'm sure the heat & pressure have the most to do with the aging & breakdown of coolant.
I've seen remnants of the GM service bulletin floating around at various websites (ls1, ls1tech,) posted by dealer mechanics/service guys supposedly, which stated the cooling system left the factory not filled properly... meaning it had air within the motor/radiator. Most likely, the oxygen in the air under heat/pressure within the motor and/or radiator oxidized the coolant and made it break down quicker than it normally would.
I'm not saying prestone is no good. It is probably great as long as it's in the correct application. All I know is that it is preached on the diesel sites, and by companies selling diesel equipment even, that say when SCA is added to ethylene glycol, it must be low-silicate meeting ASTM-4985 otherwise it should not be considered low/no silicate enough to be compatible with SCA. Someone mentioned otherwise up above. And the only reason I mentioned yellow bottle prestone is because it's the most popular and widely available, and when people go to get antifreeze they're mostly likely to get that. But it does not meet ASTM-4985 and is not a good choice for diesel's requiring SCA.
If you want a list of best antifreezes, if ti's even possible, you'll need to be more specific as to which antifreeze. Ethylene glycol, propylene glycol, dexcool type? The world of antifreeze today is archaic because there is no regulation of it. Ford has their own coolant, GM has dexcool, chrysler has theirs, and the imports have their own. And they all specifically say not compatible with ethylene gycol (traditional green antifreeze) nor any other automaker's. From what I can surmise, each manufacturer's antifreeze additive package will clash with anothers and reduce the life of the coolant at least, if it doesn't cause the additives to drop out of solution and form crud.
I've seen remnants of the GM service bulletin floating around at various websites (ls1, ls1tech,) posted by dealer mechanics/service guys supposedly, which stated the cooling system left the factory not filled properly... meaning it had air within the motor/radiator. Most likely, the oxygen in the air under heat/pressure within the motor and/or radiator oxidized the coolant and made it break down quicker than it normally would.
I'm not saying prestone is no good. It is probably great as long as it's in the correct application. All I know is that it is preached on the diesel sites, and by companies selling diesel equipment even, that say when SCA is added to ethylene glycol, it must be low-silicate meeting ASTM-4985 otherwise it should not be considered low/no silicate enough to be compatible with SCA. Someone mentioned otherwise up above. And the only reason I mentioned yellow bottle prestone is because it's the most popular and widely available, and when people go to get antifreeze they're mostly likely to get that. But it does not meet ASTM-4985 and is not a good choice for diesel's requiring SCA.
If you want a list of best antifreezes, if ti's even possible, you'll need to be more specific as to which antifreeze. Ethylene glycol, propylene glycol, dexcool type? The world of antifreeze today is archaic because there is no regulation of it. Ford has their own coolant, GM has dexcool, chrysler has theirs, and the imports have their own. And they all specifically say not compatible with ethylene gycol (traditional green antifreeze) nor any other automaker's. From what I can surmise, each manufacturer's antifreeze additive package will clash with anothers and reduce the life of the coolant at least, if it doesn't cause the additives to drop out of solution and form crud.
It's really not all that complicated. There are basically only three types of antifreeze used in the US and sold at retail, and all three are ethylene glycol based: Traditional Green which uses inorganic (silicate) anti-corrosion additives. DexCool, which uses OAT (organic acid technology) anti-corrosion additves. And G-05, which is HOAT (hybrid organic acid technology). G-05 is a low silicate formula that uses OAT additives that are different from DexCool, hence the two coolants are not compatible.
The Japanese coolants (like Toyota red) are OAT and are silicate and phosphate free. But as with G-05, the OATs used are not the same as DexCool, hence no compatibility.
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