nicam49

And thus endeth the thread !.....sounds like no-one knows the answer...OAT or IAT ...???!!!
or any update on member's knowledge?
Maybe I should just go for Prestone then....just wanted something I can buy from a shop....today!
Update several days on...
Went to an independent motor factors where the guy looked in his 'bible', then online, and entered my reg, and concluded that it needed Blue antifreeze, which was the Miller Oils brand, but he also stocked Green antifreeze, which was Comma G48 which is mentioned in an earlier post. I went for the Prestone (colour unknown at pres)

Wally2016

Hi,
What Prestone did you go for and where did you end up buying it from?

evil.soup

iTrader: (1)

God I have been reading about antifreeze for months now in various threads and it's a minefield!

Preston's antifreeze was what was recommended to me by one of the members on here that I know personally, he has been using it for many years in a variety of his Subaru's.

After reading this thread I am torn between the 2 below options:
https://www.google.com/url?sa=t&sour..._wOq4tDHcQ_WWN

Or

https://www.google.com/url?sa=t&sour...=1605430915820

Any reason I couldnt use either of these?

ALi-B

iTrader: (1)

I’d probably go for the Glystatin G40 (comma)

But when swapping brands I always throughly flush the heater matrix, block and rad.

G30 is OAT
G40 is hybrid OAT which has added silicates

The latter generally speaking is more universal...traditional straight OAT antifreezes without silicates or phosphates (any brand) whilst ok can suffer gel like sludging if the cooling system suffers from cavitation/aeration typically via a pin hole leak (google dexcool disease). The hybrid coolants don’t tend to suffer this..but the caveat is a 5yr change interval...straight OAT should last 10yrs so long as the coolant PH doesn’t go acidic (and that’s your head gasket killer...old acidic coolant eating it away).

God knows what Prestone is, they do have quite a lot of viral marketing going on.

evil.soup

iTrader: (1)

Thanks for the info. I thought Preston's was quite a well known brand and if the description is to be believed then it meets all the Subaru requirements including the alloy engine.

It's really hard to believe this is such a dark topic considering all the info out there for everything else Subaru.

Thanks again mate

ALi-B

iTrader: (1)

Prestone is a American invader so to speak (sort of like Royal purple or Redline). Been over there for years but suddenly popped up out of the blue in the UK a few years back. I doubt it imported it’s probably Holts (the UK wholesaler) using their branding under licence....afterall why would you ship gallons of it from the states and have to pay a load of import duty on something that’s cheaper to make in the UK/EU.


Honestly though it’s a nightmare. No one manufacture is fully straight with what’s in their coolant, maybe except VW/VAG which is faily well documented but still confusing (G11, G12, G12+, G12++ and G13), and the after market brands are not much better. Comma is more open with their Glysantin range which uses BASF’s specifications.

I’ve had issues with traditional OAT for other reasons; BMW use their own standards again as secretive as Subaru. Whatever that is it’s not traditional OAT...as that made the plastic go brittle in the radiator and header tank! I had two M54 engined BMWs same age and history, one with aftermarket OAT, the other with Hybrid-OAT (both had to have thermostats changed) The Hybrid OAT car to this day is still on the original rad and tank, the one using the OAT had the plastic end tanks on the radiator radiator and header tank go so brittle they literally crumbled in my hands! It took ten years for this to happen though (two coolant changes) on cars over 15years old.

Back to Subaru though...


Subaru have changed their coolants over the years as the cars have changed...early GC8’s needed traditional antifreeze as they had copper and brass that isn’t compatible with OAT, typically Japanese cars of that era typically used phosphate based antifreeze thats silicate free, usually green. You will struggle getting this stuff in the UK in this day and age except classic car stuff. You’ll have to use a Silicate antifreeze instead (usually blue), there is talk that silicates knacker water pump seals. To be honest if it did...we’d know by know...and most GC8s will have non-original pumps by now which probably have compatible seals anyway so it’s a non-issue.

Later cars are all aluminum and plastic (bar the head gasket ), OAT (G30) is acceptable, but not all cars used it used from the factory. I’m sure dealerships just used whatever their wholesaler would supply...In the Midlands the wholesaler for Castrol was Race group. Not sure who supplied Shell. My point is the dealers probably used whatever they could get from the wholesaler.

I’ve always been a bit cynical of straight OAT (silicate and phosphate free anti freezes), as whilst they last longer its anti-corrosion abilities are slower acting and they seem to have issues if air gets into the cooling system plus the mystery of the disintegrating plastic on my BMW. So on a new-age scoob it would be a hybrid-OAT (H-OAT or OAT-Si or G12++) for me which has the long term protection of a OAT but with the benefit of added silicates.


And don’t start me on what the French use...some of their factory stuff (Peugeot and Renault) looks like dishwater

evil.soup

iTrader: (1)

Now that's the kind of comprehensive answer I have been searching the web for!! Thanks for that, really appreciate it!

Now im going to go and buy some before someone else comes along with a differing opinion and muddies the coolant

Thanks again

ALi-B

iTrader: (1)

Ive done a bit more googling on Prestone.

Nowhere does it say what it contains! You probably could email Opie as they are usually pretty helpful on divulging specific details.

All the advertising just says is what it doesn’t contain (no silicate, no phosphate, no amines, no borate etc.)...I’ll just assume it’s a late generation OAT. The 10yr guarantee has a clever clause saying the car must be serviced according to manufacturer’s specs so if that mandates a 5yr coolant change your are going to have to change it anyway!


I probably should say OATs and H-OATs do vary between brands. And the OAT component of a silicate OAT is different too. I can run off a huge list of the actual chemicals typically used. But without confirmation of who uses what it’s a bit pointless.

The important thing to I can say is do not mix a silicate anti freeze with a non-silicate. That does cause gel like sludge (usually found on the coolant cap).

Hence I always say flush it and don’t mix brands. Pick one and stick with it....that’s what I said on post 16 back in 2009 and I’m sticking to that.

Incidentally I had the same trouble with central heating corrosion inhibitors when trying to investigate why a 4yr old system suffered severe black sludging and solids binding to plastic pipes. As well as hydrogen coming out of the bleed taps (always good for a laugh setting fire to the gas coming out when bleeding radiators ). I found most brands are actually not that effective.

Tron88

The non-phosphate is wrong,, Subaru states to use a Phosphate type when not using genuine] Subaru Coolant.