Hi.
I also tried it, some 10 years ago, over a longer period of time. I saw now difference, versus oil only. Now, I know that Tufoil has only 1% if PTFE, in it.
I don't see how Tufoil can do any noticable difference in any engine.
That has been my experience as well... no noticeable benefit in an engine. In other applications, such as a manual steering box, it seems to help reduce friction.