When I saw your post, I was prepared to reply by saying that you should use the Bosch Micro Edge Excel, only to see that that is what you installed!!

This has been a constant source of aggravation to me in the past.

Here are some suggestions that I think will solve the problem:

Dont use Rain-X, anti fog, or any other winshield treatment. Dont use the pink Rain-X washer fluid...it only makes the chatter worse;

Dont use any of the black stuff used to treat the wiper blade...same...makes it worse

I use Bosch Micro Edge Excell...it is the only blade that does NOT chatter for me...change annually. Every couple of months, clean the blade with straight soap and water.

NOW, The main thing that I think will solve your chatter problem is to clean the winshield with an abrasive glass cleaner or something similar. There are various products out there. I have used Meguires No. 7 polishing compound. Do NOT use something with to coarse a grit, or you will do major damage...you want something like a jewelers rouge or other VERY FINE abrasive cleaner intended for polishing glass....this will remove all the crud (minerals, fungi, etc. etc.) that will build up on th surface of glass over time.

For washing fluid, use ordinary cheap blue stuff...AND I HIGHLY RECOMMEND the Mercedes additive....it comes in little plastic ampules which you break off the end and squirt into the bottle of fluid and mix. I use one ampule for about 1.5 gallon of fluid. These cost a couple bucks each. Ive never seen anything like it...the wiper fluid goes on sudsy, but dries crystal clear...great stuff!!!

Ive also use the P-21S product.....I hated it...it left major crud over the hood of the car near the nozzles....I needed glazing compound to remove the residue!!

Good Luck,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)