[Logic]

Another forum thread where one guy tried it and everyone else ripped him a new A-hole:

Alright, guys. Remember this thread?
I decided to go ahead and give it a try. I bought a 32oz bottle about a year ago and after running seafoam for a couple hundred miles on the old oil, I changed the oil and added the Motor Silk. I made sure the OBC fuel consumption was calibrated, and I started tracking the fuel economy using the OBC. For the first ~400 miles, I was seeing the same numbers I had seen before the treatment (34.1 mpg cruising at 55mph and 31.8mpg at 70mph). After 400 miles, I began to see an improvement. By the time I had reached 700 miles on the treatment, I was seeing 37.mpg at 55mph and 34.1mpg at 70mph!

My method for testing the fuel consumption was to set the cruise control at the desired speed, and reset the OBC's fuel consumption so I could not mess it up by varying my speed. I would cruise for a long enough distance so the number would stay consistent (10 miles is usually enough), then I would turn around and repeat. That would eliminate elevation change and the wind from skewing my results.

My car had about 192k miles on it when I did the treatment. I now have 222k miles and I am still seeing the improvement.
https://www.bimmerforums.com/forum/s...otor-Silk-quot