Some rust proofings will void warranties because the contain solvents which will destroy factory applied rubberizing and other rust proofers. Krown (which is available across Canada) does not contain any solvents. It was recommened to me by an authorized Mercedes Benz Body shop (we have 2 in Toronto) I followed up by calling MB Canada and they confirmed after checking that Krown Rust Control would not void any warranties on any MB ever sold in Canada. If you plan on keeping your car, you should get it. Body rust isn't much of a problem with MBs, but if you have ever had any engine or suspension work done, the techs always tell you stuff rusts and is hard to take off and breaks and so on. Rust proofing the whole car helps out with this.

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Jason Priest
1999 E430
1995 E420 - retired
1986 420SEL - retired