Orange or Lemon/Lime?
Brother of The Benz, iodyn
You can have it with your breakfast or mix it in your filled radiator.
The Citrus Radiator Cleaner from M/B is P/N 000 989 10 25 for a 0.5kg pack.
I change the M/B Coolant every year(30%) and I've used the cleaner every year.
My 1987 300E has 177,000 miles and I'm still on the original radiator.
I've replaced the upper and lower radiator hoses one time and none of the other under the hood hoses.
Says something for the cleaning ability.
Give it a try.
Happy Trails Beep Beep from The Spiderman in Houston!!!