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Has anyone else been told this by their respective dealership?
I will ask them for the bulletin as evidence but from what I can tell 325.5 (BQ 1 03 0005) pink colour is for their truck fleet and I can't find much on it being a suitable replacement for 325.0 (BQ 1 03 0004).
Apparently it's mixable and will be used going forward.
Has anyone else been told this by their respective dealership?
I will ask them for the bulletin as evidence but from what I can tell 325.5 (BQ 1 03 0005) pink colour is for their truck fleet and I can't find much on it being a suitable replacement for 325.0 (BQ 1 03 0004).
Apparently it's mixable and will be used going forward.
The link below shows the approved spec numbers by engine. It shows the M156 is to use 325.6, which is pink. So, I'd also like to see the bulletin.
I will ask them for the bulletin as evidence but from what I can tell 325.5 (BQ 1 03 0005) pink colour is for their truck fleet and I can't find much on it being a suitable replacement for 325.0 (BQ 1 03 0004).
Where are you seeing that 325.5 was exclusively for MB trucks?
To my understanding, 325.5 replaced 325.0 a few years ago. When the head bolt job was done on my car 3+ years ago, the shop switched to the new spec (from the greenish-blue coolant that was in the car at the time to the pink coolant).
Originally Posted by FCP Euro
Following an emission update banning particular chemicals from automotive use, Mercedes revised their engine coolant formula in line with the new regulations. The new formula uses a Si-OAT (Silicate Organic Additive Technology) compound free of the borates in the .0-spec antifreeze. This pink-colored coolant originally carried the 325.5 and 326.5 designations before being superseded with the .6 formula and remains the current standard in the Mercedes-Benz and Mercedes-AMG engines. If you can’t get your hands on the official Mercedes stuff, any G40-spec coolant should do the trick.
Coolant sheet no 326.6 is compatible with coolant sheet numbers 326.64, (also 325.0, 326.0, see ***)
(***): Backward compatibility only; Products from 325.0/326.0 are not allowed in vehicles produced after 04/2014
So you can put 325.6 (pink) in older engines that were spec'ed for 325.0 (blue).
If the below is accurate on the difference between 235.5 and 325.6 then it "should" be fine.
Whatever you do, do NOT mix a HOAT (blue) with a Si-OAT (pink) coolants without completely and thoroughly flushing the system first. When you combine the blue and pink coolants, they turn into a gel, and Jell-o does not flow. There have been a number of reports of blown engines because the system wasn't properly drained of the blue stuff before someone topped it off with the pink coolant, resulting in a catastrophic failure.
The newer pink Si-OAT formulation is approved for use in all MB cars made in the last 15 or so years as it does not negatively interact with any materials in any part of the cooling system, it has the same seal conditioning, anti-bacterial and anti-oxidation properties as the blue HOAT stuff and IIRC is even better at preventing cavitation (air bubbles) at the water pump impeller, but it does require a complete system flush before it can be used. Some of the older production engines (like the early diesel OM642s) require a replacement of some seals around the water pump before the pink coolant can be used which would otherwise degrade and fail, but not the M156. The pink stuff is a newer formulation that can be used in place of the old one - they just can't be mixed.
They are compatible - as in the pink one is not going to destroy anything in a car that was designed to run on the blue one - but you can't mix them due to different chemistry.
I don't know - you'd need to talk to a chemistry major for that. Perhaps those specific ones might not gel for a while, but they will start to react with each other and end up eating various seals in as little as 24 hours... which also happens when you mix the two.
I don't know - you'd need to talk to a chemistry major for that. Perhaps those specific ones might not gel for a while, but they will start to react with each other and end up eating various seals in as little as 24 hours... which also happens when you mix the two.
Well I have a biochemistry major, and at the time when I looked at the compositions, it seemed to me that you would be able to mix them (contradicting the don't mix colors rule) which surprised me. Of course, I wouldn't say anything of that nature for fear of getting bashed on the forums but also I can't be bothered to look into it enough. Pour both in a cup and let's find out?
But also as I mentioned I could get blue from the dealer so why not just get that?
If you think I am pulling things out of my ***, all you have to do is google "coolant mix gelling". I know a thing or two about oils (but not coolants), and I used to do some statistical failure analyses for MB so I am reporting on what I saw in their data. It is a free country and it's your car though... you can run whatever you want and mix whatever you want.
If you think I am pulling things out of my ***, all you have to do is google "coolant mix gelling". I know a thing or two about oils (but not coolants), and I used to do some statistical failure analyses for MB so I am reporting on what I saw in their data. It is a free country and it's your car though... you can run whatever you want and mix whatever you want.
You appear to be argumentative with me where I am just reporting here what I have been told. Incase you misread, I didn't say you can mix them, the dealership said you can.
I will ask for a copy of the service bulletin so I can post it here. If it explicitly says you CAN mix the two, are you going to argue with "me" more?
You appear to be argumentative with me where I am just reporting here what I have been told. Incase you misread, I didn't say you can mix them, the dealership said you can.
I will ask for a copy of the service bulletin so I can post it here. If it explicitly says you CAN mix the two, are you going to argue with "me" more?
If I misinterpreted your "Oh, you're not a chemistry major? My bad..." comment, I apologize - but that definitely comes across as a snipe. And, where am I arguing with you exactly? I never took issue with anything you wrote.
I'm waiting on the bulletin and will post it up here when I have it. I did confirm again with the service manager this time. MB gave them the green light to mix the 2. No requirement to flush if one with G48 comes in and it needs to be topped up.
• Is it OK to mix anti-corrosion agent/antifreeze G48® with anti-corrosion
agent/antifreeze G40®?
There are no technical limitations on mixability, i.e. G40® can be added
in any quantity to cooling circuits filled with G48® without any need to
replace the coolant, and without using any special procedure.
• Which color is produced when anti-corrosion agent/antifreeze G48® is
mixed with anti-corrosion agent/antifreeze G40®?
Depending on the mixing ratio between both products, the blue or
mauve proportion will be increased.
I always do a flush even if it's the same coolant. Given the above, I will likely just do a single flush and not worry if there's any minor residual left over.
Last edited by Jasonoff; Oct 17, 2023 at 09:16 PM.
This is from the Glysantin site - Glysantin makes both the G48 and the G40 coolants for MB:
"GLYSANTIN® products can be mixed chemically, but we do not recommend this. Each product contains a different combination of additives that are compatible with the different materials in the cooling system. Mixing different additives can impair their overall performance and reduce the level of corrosion protection."
So, this may be what MB is relying on. Their cooling systems are generally well designed and they even put a silica gel pack in the surge tank that slowly leaches out silicate to protect the cooling system, but mixing them still goes against the recommendation from the coolant manufacturer. I too would err on the side of caution and flush that sucker regardless of the MB service information... MB mistakes always morph into huge $$$$ bills.
Converted to @BLKROKT 's favorite colour. The 2nd flush and it was dumping clear distilled water. Makes it easier with the thermostat bypass and smaller cooling capacity (no hvac or heated washer nozzle junk).
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but also I can't be bothered to look into it enough. Pour both in a cup and let's find out?
