... Nitro Benzene was a better oxyginator then Nitro methane but of course they found out that it was carcinogenic and that was the end of it. But I really did love that shoe polish smell, a fond memory of my childhood.
Remember "Blue Blazer"?
The McCoy red heads were a good design (both RR racing and front intake). If I understand correctly, after the first run or so of red heads engine manufacturers got into a price war. During this time the manufacturers of McCoy had some people who were either not skilled or required to assemble too fast and the fits were not always there. Add to that, Testor's 39 and some of the other fuels had insufficient lubrication.
Since McCoys were only about $7.00, many treated them badly; used them for a few weeks, then bought another.
I think their next attempt to regain their reputation was the lightning bolt series where they added a bronze bushing on the crank, made some other improvements, and provided better tolerances...but not for $7.00.
IMHO most of the RC fuels today are formulated for an ABC BB engine and contain insufficient quantity and type of lube to feed an iron/steel piston/cylinder setup. Although many iron/steel engines will run on 20%-22% lube, a McCoy red head or a Fox .35 should have 25%-29% all or mostly castor lube.
For an OLD iron/steel engine, I would suggest ALL castor lube. A small percentage of synthetic will sometimes clean the varnish buildup (compression aid) from the iron piston. This buildup does not occur on ABC engines.
Some are quite successful on other fuels but this works for me.
Edit: some of this was said previously. Apologies for duplication.