Oil people, does anybody add anything to their crankcase besides oil? Similarly, anyone use Techroline or anything added to their gasoline either on a routine or intermittent basis?
Not really something "besides oil", but I've been using ~5% MMO in the crankcase. On my ex-carbed F I ran MMO in the fuel regularly per the recommend dose (which I can't remember, but it wasn't too much -- something like a few ounces in a tankful), but on my TR I use the Techron concentrate occasionally (every few~5K miles -- I think you shouldn't use this too "regularly"). Try seaching on "additives" or "MMO" or "Techron" to get many previous threads.
IMO modern oils are miracle products compared to what we used to use. I just use a quality oil and forget it.
