Yep, I remember when Permatex was Permatex.
There's really no one product that will do the job right and that's why the others were developed I guess. I just use motor oil on most paper gaskets. Some places the P#2 is better than RTV, like holding the intake gaskets on a V8, but the RTV is best in other places, like where the cam cover and oil pan meet.
So what I'm saying is it has a lot to do with personal preference. You could do it all with one product like we did when there was only one Permatex. But think about the different seals you have to make and you'll soon come up with your own personal preferences. Think about, "Will this need to come off in a couple of years or is this going to stay together for the life of the engine?" For instance, the thermostat housing will be pulled long before the engine is used up. That's why I use motor oil on that gasket. It seals great and you can usually re-use the gasket instead of having to scrape and clean the area.
Get some of all 3 and you can't go wrong.
