I recently flushed and filled coolant system on my 300E with MBZ coolant. Just got car back from mechanic and saw green coolant splashes in engine compartment. When asked, he indicated that he had just topped off with the green antifreeze. I know the two aren't supposed to mix but I was wondering what if any downside exists if a small amount of green mixes with the MBZ coolant because I won't have time to address for a good while.

All help appreciated.

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2008 GL320CDI 6K
1970 280SL 112K
1982 240D 210K (Sold)
1973 220D 220K (Sold)
1967 200D 160K (Sold)
1992 400E 139K (Sold)
1988 300E 148K (Sold)
1987 300D 257K (Sold)
1991 300E 108K (Sold)
1987 300E 131K (Sold)
1978 300D TMU (Sold)
1980 300D TMU (Sold)
MBCA Member

I do not think that it would hurt for a short time, a few weeks. Many many folks use the green stuff as it has had the aluminum safe additives in it for years now. I would take it back to the mechanic and have him flush it out and add the correct coolant. I am sure he will do this no charge since he mixed the fluids. After corrected I would start looking for another one. This is something that a good mechanic would not do. Not to say the green stuff is bad but if you see the orange stuff in the tank you do not add green stuff. He should have checked it as he should have checked the condition of the old fluid before adding new. I would make the mechanic correct his mistake for sure, at least give you the money for the coolant, especially since it was fresh.

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Currently
1991 Mazda Miata 174000
1991 Subaru 189,000 Winter beater

got rid of:
1984 VW Vanagon 195,000
1976 350SE Euro 185,000 KM
1973 280SE 4.5 (boy do I regret that)
1980 280SE European W126 4 speed manual (miss it)
1989 BMW 735iL 119000 (good riddance)

Is your mechanic an MB expert? If not, the "pink vs. green" argument is a heated topic among us Benzophiles, but not necessarily to the neophytes.

I had done just that to my 300E after replacing the radiator...only had the green stuff on hand, so I went with that, until I could to a "pink" transfusion the following weekend.

I wouldn't expect any problems with the mix...worst case, the specific gravity and protection properties of the two might alter the limits of the anti-boiling/anti-freezing parameters of either of the compounds in their individual states (in other words, don't drive to Antartica or Death Valley anytime soon).

There are quite a few threads arguing this very topic, from corrosive properties, additives, and long-term wear of seals and aluminum components.

Truth is, these are observations (real or virtual) from many, many miles of use.

In your case, you shouldn't have to worry about it at all. But pick one (or the other) when you do get time.

Forgive your mechanic, but I would agree that he/she should toss in a coolant flush free of charge, as a goodwill offering.

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2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

My mechanic is owner of a strictly Mercedes Indy shop. Will probably let issue go after no charge for additional diagnostic work relating to rough idle/stumble issues (which still remain however and are a BEAR!).

It sounds like I'll be OK with the mix for a while and will therefore live with it until all other priority issues that need to be addressed have been dealt with.

Thanks.

__________________
2008 GL320CDI 6K
1970 280SL 112K
1982 240D 210K (Sold)
1973 220D 220K (Sold)
1967 200D 160K (Sold)
1992 400E 139K (Sold)
1988 300E 148K (Sold)
1987 300D 257K (Sold)
1991 300E 108K (Sold)
1987 300E 131K (Sold)
1978 300D TMU (Sold)
1980 300D TMU (Sold)
MBCA Member