Well, Skyship, when I bought my Saturn the dealership was promoting BG products including BG oil supplements. I will grant you that that was several years ago. I bought my last new car in 2004.
You do not convince me Skyship that you are some profound expert when it comes to motor oils and oil supplements. You are an investigator for warranty and insurance claims. Any oil supplement found in motor oil in a vehicle where there had been engine failure could be used (and probably would be used) as a basis for denying warranty claims. I think an investigator for insurance and warranty claims would tend to be against oil supplements.
And you have changed stories so many times, demonstrated that you did not really know what was used in German garages, and made so many incredible remarks (such as the story about a LM engine cleaner being used outside of the dealerships and garages so that there could be no liability claims) that people here are not very likely to accept what you say automatically.
To the best of my knowledge Redline still sells an oil supplement. I think Scaeffer's does too. Lubegard sells an engine oil supplement. LM, a company you seem fairly fond of, sells an oil supplement.
And Amsoil, a name brand company, sells two engine flushes.
I think these name brand companies know something and I think they make good products.
People have to have some way to clean a dirty engine that has been in use a long time and has many miles. The only other way would be to take the engine apart and physically clean it.