I feel like a broken record on this, so apologies to those who've read this before

Also hope I don't sound like I'm ranting.
I've been claying, or at least "spot-claying," at every wash for many years, since detailing clay became commonly available in the early '90s. It does *not* remove an appreciable amount of my LSPs. Period. After a year of spot-claying the MPV, mainly behind its wheels and the frontal surfaces, yeah, the KSG was sheeting, instead of beading the way it did on the rest of the vehicle. But that was after *countless* clayings. And it still felt/looked like it had plenty of KSG on there. It's all a matter of claying gently enough to "clean the dirt off the LSP", *NOT* "claying the LSP off the paint".
I've experimented with various clays, intentionally "claying the wax off", and to do this, I had to clay far more aggressively than I would normally do, and more aggressively that I believe anyone *should* do, at least on a regular basis.
With the new Sonus clay, if you remove your LSP you're doing something *very* wrong. I had to *really* work just to (intentionally) cut through Meguiar's #5 (a very fragile glaze) with it. I've since also used it on KSG, UPP and Meg's #16 and it didn't hurt them either. But then the Sonus gray/Mother's/Griot's clay don't strip them the way I clay either
If the contamination you want to remove is *under* the existing LSP, then yeah, you have to get through the LSP to remove it. You can either strip the LSP (the method *I* would use) or clay very aggressively, which might cause marring (which would require polishing, which would've done the job all by itself anyhow).
pontman43- It's a safe bet that the stuff on your dad's car *is* just another bulk-packaged sealant. You could probably get his car looking a lot better with a good clay/polish/LSP routine. But I know how father's can be about stuff like this

Maybe you oughta do some other car first and show him what a great job you can do. Or you could just wait until the Touch of Class starts to fail and then say (*nicely*) that you told him so and offer to fix it up for him. Heh heh, that's what I did, but then I was stuck doing the family cars from then on.