Silicates and Aluminium

[FCD]

I've read on various papers on coolant that silicates are added to coolant primarily for protecting aluminium engine parts.

I have read on other places that for example Honda genuine coolant does not contain silicates, because they believe it is hard on aluminium engine parts.

What is the consensus? good or bad for alu engine components?

I've also read Borates are definetly bad on Alu, true?

 

[skyactiv]

The auto makers have differing opinions on coolant technology.

 

[FCD]

Haha yeah i've been trying to wrap my head around all the different VW G specs of coolant, OATs, IATs, HOATs and what they have or do not have and etc and it really doesn't make any sense.

 

[SZR48207]

I thought silicates were used to clean surfaces of scale buildup?

So then with changes in material tech, the switch was made to OAT which is just as effective at cleaning scale from surfaces.

Scale buildup would adversely affect heat transfer.

The problem with silicates is that they fall out of suspension with time and would sit at the lowest portions of the cooling system. An OAT can't fall out of suspension which gives them a longer service life.

 

[Kage860]

Just different systems, both seem to work fine. Silica seems to be more of a jelly-like substance that coats everything, more oldschool. Asian OATs use different chemistry which includes phosphates. The silica seems to protect the metals “faster”, but may cause wear in certain circumstances. ( i.e., water pump impeller material becomes more important) OATs take a while to protect, so asian coolants are sold as 50/50, they dont seem to want water in the system, just drain and fills with 50/50 to maintain protection.

 

[Kage860]

So the way I see it:

G-05 - More tolerant of impurities (tap water, air, other coolants, etc) Can be used in virtually any engine cooling system.

Asian Coolants - Possibly better coolant if you keep to the system and don't mix with tap water, other coolants, let air in, etc.

 

[SZR48207]

Originally Posted By: Kage860
So the way I see it:

G-05 - More tolerant of impurities (tap water, air, other coolants, etc) Can be used in virtually any engine cooling system.

Asian Coolants - Possibly better coolant if you keep to the system and don't mix with tap water, other coolants, let air in, etc.


G05 being a HOAT (hybrid organic acid technology) -- you will see it often used as a 'middle of the road' solution where the original factory spec may have been conventional silicated green. Ford did this in 2001/2002 when they went to Motorcraft Gold on vehicles that had been spec'd with green.

But if it came with OAT.. I'd stick with only OAT.

And if it came with conventional green.. whatever floats your boat.

 

[FCD]

Jus trying to decide whether to use a more expensive G12++ Si-OAT or a plain G12+ OAT with no silicates, that is somewhat cheaper.

 

[nthach]

Originally Posted By: FordCapriDriver
Jus trying to decide whether to use a more expensive G12++ Si-OAT or a plain G12+ OAT with no silicates, that is somewhat cheaper.

I think G48 or G40(BASF's tradename for what VW calls G12++) will be fine in your car. The wildcard would be gasket elastomer compatibility but if Mercedes backspeced G48 for all their cars using G05 you should be OK. G13(Glysantin GG40) is a less toxic version of G40, with glycerin replacing part of the ethylene glycol in it.

 

[FCD]

I think i'm going to go for G13, went to the shop that was supposedly had that G12++ Si-OAT and they no longer stock it.
G13 is basically an Si-OAT so just what i'm looking for.

 

[FCD]

deleted

 

[Chris142]

Most of the gm plastic/aluminum radiators I see today have electrolysis damage. We never saw that kind of damage before 1996 when gm went from green to dexcool.

 

[FCD]

Isn't Dex Cool supposed to be similar to G12, in that it's a plain OAT with no Inorganic additives?
I want the Silicates but nothing else in my OAT

 

[Omahaug]

To my knowledge silicates have less to do with anything specific regarding aluminum and more to preventing just corrosion and scale build-up in general. Whether it's corrosion on aluminum (oxide) or iron (rust).

Silicates wear on things like water pump seals and coolant with silicates requires shorter change intervals, the industry has now mostly moved to coolants that are silicate free, they achieve their corrosion protection in other ways (like OAT).

 

[FCD]

Originally Posted by NoNameJoe
To my knowledge silicates have less to do with anything specific regarding aluminum and more to preventing just corrosion and scale build-up in general. Whether it's corrosion on aluminum (oxide) or iron (rust).

Silicates wear on things like water pump seals and coolant with silicates requires shorter change intervals, the industry has now mostly moved to coolants that are silicate free, they achieve their corrosion protection in other ways (like OAT).

It used to be believed that silicates did cause wear on water pumps but it has been disproven as far as i know, i've been reading up on this quite a bit since i made this post.
VW switched from G11, a regular IAT coolant, to G12 , and G12+, both of which are full OATs with no inorganic additives.
However witg G12++ and G13 they have now put Silicates back in to their Coolants! i don't think they would have if it had negative effects.

 

[KrisZ]

The main function of the silicates and phosphates is protection against cavitation. They very quickly form a protective film on the surface. OAT coolants form the same protective film but at a much slower pace.
Also, silicates are much more tolerant to hard water, unlike phosphates.

 

[PandaBear]

So it seems like the solution is phosphate coolant with de-ionized / distill water, or OAT coolant if factory fill?