Kind of hard to get a complete track assembly that's got links so tight they won't hinge into a bath so I'd really like to see how those guys are doing it cause I don't have a tank that big. That said when my customer first got his machine about 6 years ago we beat and heat on the tightest links, saturated them in penetrating oil, and eventually just kept them soaked in diesel every tieme he finished running it. Over the course of several months of doing this they tracks were still tight.
That said setting here thinking about this situation, I wonder how using something like a rust remover would work. I know I've used a product made by ZEP that will remove rust and leave you with bare metal with enough applications. I wonder if that stuff would penetrate into the links on a set of chains and help free them up.....Might be worth a try.