The #81 PHP is a finer polish than the #82 SFP and yes it does have oils that will be removed by AIO. It will still polish the surface a bit finer than SFP so it won't be a futile process. Again, it all depends on how far you want to take it. One thing about sealants is that good preparation makes huge difference in the final appearance. AIO/SG can be unforgiving and bring out the flaws in the paint which is why I use a swirl remover (ie. Poorboys SSR1 or Megs #9/#82) and a finer polish (ie. Poorboys Professional Polish or Megs #81). DACP can be used for more severe swirls first.
So to reiterate, it's not essential that you use a finer polish, but it does help.
Any more questions, just ask. Hope this helps. Hey, BTW, post some before and after pics! I love pics!
Jeremy