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Have seen varying information online regarding the color of the coolant when adding. I have a 2015 GLK 350 that currently has coolant that appears to be orange in color. Is the correct coolant supposed to be purple in color? Went to AutoZone and that is what they recommended. I believe that it is not good to mix colors? Should I flush the coolant and fill with the purple coolant?
Have seen varying information online regarding the color of the coolant when adding. I have a 2015 GLK 350 that currently has coolant that appears to be orange in color.
Is the correct coolant supposed to be purple in color?
Went to AutoZone and that is what they recommended. I believe that it is not good to mix colors?
Should I flush the coolant and fill with the purple coolant?
All the right questions show you understand to be careful not to mix-up your coolant chemistry.
We have seen serious damages from mixed-up coolant.
You already running orange... the single best chemistry is the OE type.
Double-check your engine specs for ZEREX G05 YLW Coolant later superseeded by G48 Turquoise blue...
YLW equals BLU
I'd seriously stick with the OE type regardless of MB later changes to G40.
why stick with G48
In the COOLANT & HEAT chapter: damages caused by accumulated heat in these engines are not caused by wrong coolant type but repeated heat soaks after engine stop.
Last edited by CaliBenzDriver; Nov 9, 2025 at 11:11 PM.
Do not mix the orange and purple coolants.
For your 2015 GLK 350, the purple coolant is the new, correct specification.
You should do a complete flush to remove all the old orange coolant before filling with the new purple type.
I have been using the Zerex brand coolant. I buy it already pre-mixed 50/50. When I had some work done at my local MB dealer on the bill they charged me for "Zerex G48 coolant" which is what I have been using.
As noted above use the MB Bevo website if you are not sure which spec to use. My operators manual in the glove box lists which specific spec coolant to use. Cant really go on what color coolant is in the car since the previous owner could have used the wrong coolant, if it is a used car.
Napa auto parts usually has the G48 and G40 coolant on sale which is where I get it.
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