Crenwelge, you sound like you have some credibility having had a dad who sold lubricants and additives and you took over the business and are now selling them. I don't think you could sleep at night if you knew they were somehow harmful or at the least, not beneficial. I'll consider your comments an endorsement.
Stuart, I tend to agree with you about a worn engine, but I have also read that certain additives can improve the condition of dry seals, and can reduce the gap between parts to the point that it can reduce smoking, etc. I think I'll put a bottle of STP or the like in the old 6-banger and hope for the best until I can rebuilt it one day.
Thanks!
Chuck "Spot"