When it comes to maintaining a Mercedes-Benz, choosing the correct fluids is crucial, and antifreeze is no exception. For years, I’ve relied on Zerex G-05 antifreeze in my Mercedes, with excellent results. My research into Mercedes coolants has led me down a bit of a rabbit hole, comparing it to the factory Mercedes-Benz coolants and some interesting discoveries about the newer blue formulation.
Like many Mercedes owners, I initially assumed that sticking with genuine Mercedes-Benz coolant was the safest bet. In the past, I used the orange Mercedes coolant without any issues. However, delving into the Material Safety Data Sheets (MSDS) and technical documents revealed some compelling similarities between the older Mercedes orange coolant and Zerex G-05. In fact, Mercedes orange coolant is also often referred to as a G-05 type formula, though it’s unlikely they are exactly identical due to proprietary formulations. The primary difference I could pinpoint, and this could simply be a matter of naming conventions, is that Mercedes orange coolant lists Sodium Tetraborate while Zerex G-05 contains Disodium Tetraborate Anhydrous. Perhaps a chemist could elaborate on the significance of this subtle difference.
My preference for the orange coolant, or G-05 equivalent, was also driven by a desire to maintain the same coolant color during flushes. Switching to the blue Mercedes coolant raised some questions for me, not about its overall quality, but about its formulation compared to older Mercedes models. Mercedes-Benz documentation describes the blue coolant as being “slightly different in that it adds more organic acid, along with its basic silicate additive.” Specifically, older Mercedes coolant information highlighted the absence of 2-ethylhexanoic acid (2-EHA), noting: “2-EHA (2-ethylhexanoic acid) is a “plasticizer,” which means it softens plastics. Gaskets are made with plastic and there have been laboratory tests reported by other manufacturers, that raise concerns about coolant-sealing gasket leakage with 2-EHA.”
Intriguingly, 2-EHA is a key ingredient in DexCool, a coolant known to have caused issues in some vehicles, particularly with gasket compatibility. While I trust that Mercedes-Benz engineers have thoroughly tested and mitigated any potential problems with 2-EHA in their new blue coolant, its inclusion, after previously noting concerns, makes me cautious, especially for older Mercedes models with potentially aged gaskets.
Therefore, until I am completely confident about the long-term effects of 2-EHA in the blue Mercedes Antifreeze on older vehicles, I plan to continue using Zerex G-05. It’s a known quantity, and its similarity to the original Mercedes orange coolant provides peace of mind. This isn’t to say the blue Mercedes coolant is inferior – in fact, it’s undoubtedly a superior choice compared to generic green coolants like Prestone. However, for classic or older Mercedes-Benz vehicles, especially those with original gaskets, sticking with a G-05 formulation like Zerex might be a more conservative and informed decision. Choosing the right mercedes antifreeze is a critical part of preventative maintenance and ensuring the longevity of your engine.
