1, Play a few seconds of a favourite tune, then play the same thing again - you *may* hear a difference in the treble, the second listening a little sweeter. i don't have the references, but this aspect was done to death in the eighties, when higher tracking weights of up to 2 grammes came back into fashion.. If you can't hear a difference, don't worry, it's probably the brain/imagination getting in the way and making up differences;)
The Hunt P2 was the kit you refer to. Halocarbon 113 I think it was (a chemist client analysed it) and a blue oily substance on top to prevent evaporation. Jimmy introduced me to it and I found it livened up the sound no end, but dramatically increased surface noise. Records thus treated reverted to their previous state after a short while I found and it was such a pain to use.
There was another disc-washing system marketed by "Cantorion" back in the late eighties/early nineties, which was a bit more sophisticated and longer lasting, but memories are very vague.

