BigDave,
I have not used the Hot Shot Secret friction reducer, but I would not recommend using it or any other oil additive. The reason I say this is that every oil that is on the market has additives that are built into it when it is blended. This blend is proprietary, the blender protects their blend as a trade secret. All of the different additives that are in the blend are in balance, adding more of one additive will effect the performance of other of the additives, quite likely in a negative way. So how can an additive company, without knowing what oil you will be adding it to, come up with an additive that will make the oil better than the original blender could? It will not help in the best case, and in the worst case, might throw the additive balance off and provide less protection.
From what they advertise, Hot Shot Secret is an ester, which is often used as the base for synthetic oils. Do yourself a favor, and just purchase a good synthetic motor oil, and forget the aftermarket additives.
In regards to the fuel additive, that is a bit different, the fuel blenders will use the minimum federally mandated additives to keep costs down, so there can be a benefit from fuel additives, but I would be leery of which company I purchased the fuel additive from.