Coolant type
 

Alright, dumb question, what coolant does my 2014 ML350 take? Currently it appears there is yellow in the reservoir (car has always been to a dealer so im certain someone didnt put in generic prestone and im assuming it was yellow from factory in 2014). I went to the MB dealer and they sold me a jug of blue Zerex. I told him i expected to be getting mercedes branded coolant and he informed me that there is no more mercedes branded coolant and dealers have been instructed to use zerex. I later went on the zerex website to confirm and plugged in the vehicle information, it came back and said the pink one was correct. So now Im confused, what does this car take!?!??!

Lastly, I know I need to figure out where the coolant is getting lost but want to get it topped off first.

I recently changed coolant in my 2014 ML350 4matic (gasoline). I bought a gallon of Zerex-G48 and bought one gallon of distilled water and mixed the two. Zerex-G48 conforms to the required spec. for my vehicle.

325.0 and 326.0 up to and including April 2014 build date. Zerex G48 is one option. https://operatingfluids.mercedes-ben...sheet/325.0/en
325.6 and 326.6 after April 2014. Zerex G40 is one option. https://operatingfluids.mercedes-ben...sheet/325.6/en

^ This - or just replace it with OEM Mercedes coolant... blue (BQ1030004) or pink (BQ1030005) respectively. They add proprietary anti-corrosion, anti-bacterial and seal conditioning stuff that works for their specific application.

I tried to replace with OEM MB branded coolant. The guy in the parts dept at the dealer told me they dont sell the MB branded anymore and that this zerex has superseeded it.

Thanks, this is perfect! The sticker in the door jamb says Alabama 9/13. So it looks like ill be going with the blue G48 option.

That's a first - Mercedes not wanting you to use their own fluids!

The yellow coolant was the original one Mercedes used (part # BQ1030002) ~20 years ago and was a G05 spec, which was superseded by the blue one (BQ1030004) which is a G48 spec. Both are HOAT type formulas. The yellow coolant hasn't been used for at least ten years now, and seeing as Merc calls for a coolant flush every two years or 30,000 miles (which arguably you do need to perform on any turbocharged car as they produce more heat and are more likely to lead to engine / component failures as a result of it not being repalced), if you've still got yellow coolant it has either not been changed since the car was new and has lost all of its protective and even cooling properties a long time ago, or it was changed with an unapproved coolant - so in either case you've likely got bigger problems as a result of it not being replaced and is why you're losing it somewhere (hopefully not through any part of the engine itself).

The pink coolant is the latest G40 spec, Borate-free Si-OAT type formula that you *can* use in the older engines but only after all of the old coolant has been thoroughly flushed out of the system, which is probably why the Zerex site is telling you to use the pink one.

I too was surprised that they didnt have over priced mercedes branded coolant ready to sell and even more surprised that he said they dont carry that anymore, per MB. Perhaps the guy was blowing smoke up my ass and maybe the non genuine fluids are easier to get or they get a better markup, who knows.

Im surprised that MB calls for a coolant flush every two years (you are correct here) but its not listed in service A/B. I purchased the car from my mother who has always taken it to the dealer for every last little thing. Maybe somewhere along the line they flushed it for her but its surprising its yellow. At this point, I guess Ill get some prestone coolant flush and flush the whole thing out several times over the weekend. Then I just have to decide between the blue and pink, if the pink is the latest and greatest, maybe Ill go with that one.

The pink is Borate-and-some-other-ester-based-chemical-free, and AFAIK it is supposed to be safe for all previous Mercedes engines but does not play well when mixed with the blue / yellow one (they have different chemistries that are not compatible and if mixed will cause damage in pretty short order). I hope you find where the leak is and hope it's something minor, i.e. inexpensive. But yeah, on a turbo engine I'd flush the coolant every couple of years because it does lose its ability to absorb and transfer heat just like it loses its seal conditioning and anti-oxidation properties. Even in race cars that are run on the track and can't use coolant, we add WaterWetter to increase heat transfer ability and cooling system protection so it's the same idea here.

Maybe I’m in the wrong sub forum, but my w166 doesn’t have a turbo and is NA. I haven’t spotted any leaks yet but hopefully as I’m flushing it, I’ll be able to locate it, and like you said… really hoping it’s cheap!

As for the water wetter, I’ve completely forgotten about that product. I used to run it in decades back in my turbo supra and turbo dsm!

You are in the right forum.