5.0v8 antifreeze compatibility?

[Somebody]

Does anybody know if the 5.0 v8s of later 1980s vintage are compatible with organic-acid based antifreeze?

Thanks

 

[millo777]

I've been looking into the same for use in my w140, and it seems what it comes down is the newer OAT coolants aren't compatible with yellow metals, so if the engine has any copper or brass in the cooling system, it's not usable.

There is also the problem that the OAT coolants are not comptabile with the older IAT types, so changing types requires a very good flush to remove all of the old type.

My conclusion for my own cars is that the MB coolant, which is apparently a hydrid OAT forumulation is the best option. The spec sheet is 325.0, and the part number is A000989082511 for 5L and costs £25.81 from the main dealer (with 10% club discount)

325.0 should be the correct spec for the m117 engine.

Part of the motivation, is that MB now recommend a 15 year/150,000 mile change interval for this coolant. I doubt I'd leave it that long for a coolant change, but I've read that 10 years/100,000 miles is about right.

 

[Somebody]

Yeah, from what I gather yellow metals is pretty much the only issue. I run OAT in really old engines (like 1960s), as long as you replace the copper-core radiator with a aluminum one, and replace the brass thermostat with a modern steel one, and occasionally there is a small brass insert in the coolant pump that needs to be replaced, and it works well.

But, its kind of hard to tell from the outside if the 5.0 has any yellow metal components, its surprising how many cars have yellow metal components in the cooling system and people don't even know about it.

I will be completely replacing the coolant so the whole thing will be completely flushed and cleaned, so intermixing is not a issue.

But, looking at the spec sheet, a few of the products it lists are G48, which is pretty handy since G48 is a reasonably common product.

But G48 is a 3-year antifreeze, and was probably top of the range in the 80s when they made these cars, but since then it has been superseded with OAT based products, which are much better.

So, in your looking into using OATs, did you figure out any reasons specifically to NOT use it?

Because from what I understand, if you want the best for your engine (and lets face it most classics are living way past their shelf-life in a world for which they were not designed) then its a good idea to use OAT based products unless there is specifically a reason not to which you cannot remove (like, for example yellow metals used somewhere in the cooling system which you cannot easily replace with a non-yellow equivalent).

 

[millo777]

I looked at the G48, but Comma state a 3 years typical service life, and the MB dealer stuff is only a £5 more which seems worth the extra.

Strangely, the MB antifreeze is almost certainly made by Febi (The bottle ares identical), but the Febi brand isn't on the approved products list.

 

[markjay]

One other advantage of the 15-years coolant change is less sediment.

Every time the coolant is changed new sediment is introduced into the cooling system.

Think about it this way - if you only ever boiled the same water in the kettle, it would be much cleaner than when boiling new water every time...

So a good quality coolant that does not need changing will prevent many cooling system issues.

 

[Somebody]

Well, thats weird. I think we just found yet another anomaly in MB's recommended fluid lists.

The thing with numbers like G48 or Dextron III or GL5 or the like is that they are all supposed to be the same. So, one brand's GL5 fluid is the same (or functionally interchangeable at least) to any other brand's GL5 fluid.

So if G48 is on the recommended coolant list, that means that every other product on that list is also a G48 type product, because otherwise it wouldn't be on the list, right? So that means that Mercedes main dealer fluid is basically their version of a G48 product, otherwise it won't be on the same list as other G48 products.

So how can it have a 15 year lifespan whereas generic G48 has a 3 year life span?

Sediment is not a issue if you use deionized water (or premixed coolant) and don't like, dig the earth in your back yard with your header tank or something lol. But there is no doubt about it, OAT coolant is much better for older engines. Anybody who ever took engines apart will confirm, the corrosion inhibiting action of OAT is so much better.

 

[millo777]

Bear in mind that Benz also told customers their transmissions were sealed for life and didn't need a change of fluid.

Whats really strange is that the 325.3 spec coolants for newer cars is often referred to as "Long life coolant".......as opposed to the supposed 15year life of the lower spec?

From what I've read the 325.0 from the dealer is a hybrid OAT coolant, whatever that means, so should be compatible with older engines but still with a longer service life.

 

[Somebody]

I am sure the 15 year thing must be a mistake or something, because, like you said, 5 year coolant life is long even by modern standards, if 15 year coolant was practical than surely nobody would use OAT anymore? I dunno.

Transmissions being supposedly sealed for life is annoying, but a lot of manufacturers do it unfortunately. Some don't even provide a way to drain the transmission which is totally super annoying. Then again, I guess, cars are designed to last about 10 years right?

I am not entirely sure what hybrid OAT is either. I always assumed there was IAT (usually blue), OAT (usually red) ,and a few manufacturer-specific mixes (such as G12, because VW were stupid and didn't plan their entry into liquid-cooled engines very well), and that's about it, thats basically mankind's whole achievements in coolant technology. OAT is superior in every way except for the fact that it eats yellow metals. IAT is not as good but doesn't eat yellow metals.

The only people who should still be using IAT are people who have like 1910s cars with big shiny polished copper radiators and pipes and such, or people who have yellow metal components deep in the cooling system that they can't easily replace.

 

[markjay]

I am sure the 15 year thing must be a mistake or something...

No mistake... it is printed black-on-white in every Service Book from around 2004 and up to the point they moved to ESS.

 

[millo777]

http://bevo.mercedes-benz.com/d/d/en/Spec_310_1.PDF

I've also just read that the vehicles with the 15 year change interval from the factory were fitted with some form of silica gel packs in the expansion tanks that topped up the corrosion inhibitors. Hence the 15 year interval only refers to those cars?

So from what I can see, the m117 would need the HOAT anti freeze and a 3 year change interval.

Same for the m120 I looking to do a coolant change on.

 

[hotrodder]

MB325.0 includes both G05 and G48 flavours which are both HOAT types. The long life* thing, as said, is as much about the silica packet stuffed in the header tank as anything...

IAT and OAT corrosion inhibitors work in very different ways. The former basically 'coat' surfaces and then sacrifice themselves and different flavours work differently on different metals hence the old fashioned IATs containing a mixture of silicates, phosphates, borates etc. Very crudely OAT inhibitors kinda wait for corrosion to start and then react chemically arresting it i.e. they only get to work when & where needed and so naturally last longer. As with IATs there are various different flavours and recipes which are tailored to a different mixture of metals/plastics. It's not as simple as OAT eats yellow metals...

Some flavours of OAT have been shown to attack plastics and gaskets materials, google Dexcool lawsuit...
Some flavours don't offer much protection to yellow metals but AFAIK it's usually the solder used in copper rads that's left the most vunerable

MB (and BMW amongst others) have gone with HOAT for a couple of reasons. Some of the IATs used in traditional coolants can actually promote the build up of scale in the system if hard water is used (phosphates IIRC) but straight OAT coolant isn't so good at providing long term protection to areas subject to cavitation like the waterpump for example. Many (most?) or the manufacturers that choose OAT coolants use timing belts which also drive the waterpump and as a result the pump is pretty much considered a consumable because if it dies there's a good chance it'll take out the belt followed by the engine...

Of the IATs silicates work very well at protecting aluminium which is why MB stuff a silica pack in the header tank to slowly leech silicates into the coolant as these get depleted with time. This is where the long service life comes from, not the coolant itself. G48 is an OAT coolant with silicates while g05 contains silicates and nitrates. Data sheets here...
http://www.geomatique-liege.be/MGJP/DocumentsPDF/Coolant/Glysantin_G48.pdf
http://www.geomatique-liege.be/MGJP/DocumentsPDF/Coolant/Glysantin_G05.pdf

Note the differences in the corrosion tests, g48 is better for aluminium and a fair bit worse for yellow metals relatively speaking- both exceed the ASTM limits by miles. Look up the data sheet for g30 (OAT) and it's cast iron that jumps out while still being well below the ASTM limits. G40 which is a relatively new hybrid Si-OAT looks good for pretty much all the common metals found in engines... http://www.orvema.nl/Productbladen/Glysantin G40.pdf, note they're starting to get pretty specific testing specific alloys of aluminium etc


* the long life/sealed for life/extended service interval thing is more about appealing to fleet buyers/rental drivers than the longterm survival of the car in the hands of an enthusiast [/gross generalisation]

 

[markjay]

I wonder if when replacing coolant due to other repair work (faulty pump, leaky rad, etc), the Silica Gel needs topping up?