For what it’s worth, my experience of Dinitrol.
I’ve had a 1972 MGB and my 2002 Td5 both done by a professional in Glasgow. I’m super pleased and his work really got into the nooks and crannies. Took 4 days to allow the jet and steam clean to dry and the final coating to go off. But here is the killer benefit......he provided an interior camera film on dvd of the whole box section after it had been cleaned and then treated. This gave me some perspective of what risk I was dealing with rather than the ‘shooting blind’ approach.
I echo the comments about what you can’t see is the problem, it’s been on on 3 years and since then the two areas of the chassis that were in need of repair have been done, but the treatment has held together, it’s not thick and crud like on fittings and the ability to keep an eye on your truck remains.
I’m a fan, it was well worth the 500 spent as the products alone were close to 200.