Charles, I have found that #105 isn't capable of removing Zaino products or Klasse AIO so the cleaning power isn't that strong in 105. When not doing a real cleaning with a product such as Klasse AIO, it's definitely necessary to go over the car with the #601 PBA and then applying #105.
Since I tend to more or less group the products I use, I have certain products I use with others
When my LSP is #105, my initial prep will be with #501 as the cleaner/prep, #601 because Duragloss recommends it, #105, and then Aqua Wax 2 or 3 times a month.
I only do the complete cleaner prep thing 2 or 3 times a year. I do apply #105 every 4 to 6 weeks and rarely use the #601 at that time. I figure the #105 should bond to the #105 and it's cleaning power should be enough in that case.
When I use Opti-Seal as my LSP, my cleaner prep is Poli-Seal at the same 2 or 3 times a year intervals. After the Poli-Seal/Opti-Seal application, I use the Aqua Wax 2 or 3 times a month and add another application of Opti-Seal every 4 to 6 weeks.
When I use Meguiar's, my prep is #80 followed by several different Meg's LSPs over the years.
My methods may not be for everyone, but they work for me. I haven't had much incompatibility problem with different manufacturer's products on the same vehicle, but I did have it one time. My LSP smeared the cleaner/prep quite badly and I never used that combination again. It happened to be a 3M product and a Meguiar's product. Since they are now one big happy family, they would probably get along great together today.
The only vehicles I take care of are my own and they are never in very bad shape to start with. Keeping a car up is a heck of a lot easier than resurrecting one.
