Sounds tantalizing, as do long-term effects, but I’d like to know if the claims are real. My ‘64 Imperial was owned by a spinster who lived to 105 (imagine driving with gloves/hat at 40% of posted speed limit) and there was considerable sludge on top of the heads when I pulled the valve covers during a seal and painting excursion a few years ago. I cleaned what I could but fear more exists elsewhere.
This Valvoline product sounds like it would be a good solution, perhaps there are others as well?