Yesterday I had a long discussion with our long-time member Dave Gallon regarding coolants for the Pagoda. I’ll try to include facts only. I have ignored a lot of old posts on the matter that you’ll find on various MB forums such as
MB World, PeachParts, etc. since some of these were old and were all talking opinions instead of facts—and could be talking products NLA or ones reformulated over the years.
Our cooling systems are truly multi-material. There’s brass/copper (OEM radiator and overflow tank); iron (block); steel (cover plates on engine) aluminum (head) and organic parts such as rubber hoses and seals. A very modern engine might be less with no copper/brass but plastic. I understand some modern Mercedes include a disintegrating additive pack which keeps the anti-corrosion additives going in the coolant. We don’t have this.
Here are some facts: the “modern” (meaning not in 1970) coolant specified for our cars from Mercedes-Benz was their own private label product, with the part number Q-1-03-0002. However that has been discontinued and is “NLA”.
https://www.pelicanparts.com/More_Info/Q1030002.htm?pn=Q1-03-0002-MBZIf you go to some of our usual suppliers to try and find that, you’ll see a note that it was
replaced with Q-1-03-0004. That too, was made NLA:
https://www.pelicanparts.com/More_Info/Q1030004.htm?pn=Q-1-03-0004-M22What you are directed to as a replacement is one of the many products with “G48” in their name, so for example see this:
https://www.autohausaz.com/pn/Q1030004So two issues arose in the discussion with this: first, is the Zerex branded G-48 the exact formulation as the prior Mercedes branded Q-1-03-0004? The other issue is that empirical evidence offered by Dave Gallon from his work at Motoring Investments (Brian Peters in San Diego for those that need a refresher) is that the -004 formulation (as opposed to the prior -002 formulation) showed some signs of corrosion on engines. You will note that there is reference to Mercedes-Benz approval 325.0 in some of these product listings.
https://operatingfluids.mercedes-benz.com/sheet/325.0So from that 325.0 specification from Mercedes-Benz, you’ll see that “application for all passenger vehicles…prior to April 2014”. Sounds good. OK, now since Zerex (this is mostly for USA and North American members) is one of the most popular and readily available brands, and is on the list above, let’s go to their website, and scroll down to “European Vehicles” and you’ll see just three products: G-30, G-40, and G-48. The G-05 is listed under “Heavy Duty Vehicles”.
https://www.valvolineglobal.com/en/antifreeze-coolant/The G-30 is an OAT coolant. The G-40 is OAT. The G-48 is HOAT. The G-05 is HOAT. All are EG based.
So was there any conclusion? No. If you go to the usual suppliers, you’ll get referred to the G-48. However, if you read the spec sheet on the G-05, that sounds fine too.
You cannot purchase (unless it's NOS sitting on a shelf somewhere) Mercedes-branded coolant at least in the USA, any longer. So you need to go with an available product. When doing mine recently I chose the G-48 since that was what I was pointed to.
I could read the spec sheets on the G-05 and reach the same conclusions, however. One thing I did is buy the pre-mix, taking water quality out of the equation. Premix is mixed with purified and de-ionized water. BTW, if you look at the specs on any of these, at the 50/50 mix rate they seem to show a pH of about ~8.0. Slightly basic, not acidic.
What are all the differences? The amount of additives, silicates, nitrates, etc. I’m not a chemist so I don’t know which is any better than any other. Dave and I ended the conversations last night with my final word on it: the best coolant (like oil) is probably the one you change most frequently.
If anyone has more to add to all this, post away.
Sidebar for the chemists among us: if you go to that Mercedes 325.0 spec, you will see a lot of products with the number “48” in their name or description. What’s magical about this number?
