Hi everyone,

I have a low coolant indicator and a gallon bottle of MB "anticorrosion/antifreeze agent" (part no. Q 1 03 0002).

Do I just pour some of it in as normal? I've read a bit about not mixing coolants, although I don't know what coolant is in there now. (the bottle does say, "MB anticorrosion/antifreeze agent may only be mixed with other manufacturer's agents provided they have been approved by MBNA). I think the fluids were all flushed not long ago.

Is this car picky about what it uses? Can I use off-the-shelf auto parts store grade coolant if I ever wanted to do that? Or, do I need to be sure to only use this MB product and drain anything else that is in there?

It says that MB recommends a 50/50 mixture. I live in Arizona.

Thank you for your input!

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1980 300SD (daily driver), 1981 300D (Inca Red)

The car is indeed picky (or at least its engineers were) but the stuff you have meets the spec.

You should never use generic coolant. Zerex G05 also meets the MB spec.

The stuff you have is, I believe, full strength. So you should mix it with distilled water.

More importantly, you need to find your leak.

A common point would be the weep hole for the water pump, which is mostly hidden behind the pulley. Take a quick look with a flashlight from above, if it's not evident spend the time necessary to pull the belly pan (it's not that bad, and that way you can dump all the accumulated sand, dirt and leaves out of it, too). Then you can look up from the bottom and have a better angle on it.

If there is absolutely zero evidence behind the pulley (even no dried "tracks") then check the windshield fluid container. Engine coolant is cycled through a coil in it and the hose connections can develop leaks.

But needing coolant is not normal, so be sure to follow up. And that way you don't need to worry about whether what you have is okay to dump in between changes.

Good luck.

assuming the coolant in the car is green, they can be mixed. BEST is to dump all the stuff in the car, flush it good and use the whole gallon plus water, 50/50. the mb coolant has no phosphates in it which react with aluminum, and there's lots in that engine. if for some reason the coolant is orange(not from rust), which i seriously doubt, it HAS to be dumped and flushed MANY times as that stuff and most normal coolant do not get along. remember, i'm assumng. i can't see your car, there light here sucks. good luck, chuck.