Never say never. I "never" heard of this line of products before, but I found this website because my independent Mercedes shop told me that they used Lubro-Moly as an additive during the oil change included in an "E" service. Well, I had to know what the stuff was, and that search for information on the products led me here.
True, Mercedes does not officilly endorse or recommend the use of any additives, fuel or engine. But Mercedes dealers sell Redline products in their parts departments. So why don't they sell Lubro-Moly? Well, according to Jerry Boyd, the company's marketing strategy is focused on making their products available only through independent garages and the internet. They have no interest in selling it through auto parts stores, or Mercedes dealers. If they did sell to Mercedes, I think that the additive policy would change, but what we're dealing with is politics, not just engineering.
When your Mercedes warranty is no longer an issue, there is no reason not to try this excellent line of quality German products. For a more complete picture of the company and it's products, go to: http://www.liqui-moly.de.
The parent compant in Germany is known as Liqui-Moly in Europe, and Lubro-Moly here in the U.S..