[oil pan 4]

Yeah I saw that. The tests used employed bottle fed hydrogen and appear to use far more hydrogen than an hho machine can make.
The one test showed that adding hydrogen improved fuel economy by a third. How do we know they induce a problem and then fake fix it with hydrogen.
The best way I can think of would be to run the engine at low load, at mid range RPMs, retard timing to reduce fuel economy and then add hydrogen because we know hydrogen burns really fast to make it look like the hydrogen increased fuel economy.
Where if the engine was running properly the hydrogen would have only increased fuel economy by a lab measurable amount.