Lee, as I previously stated:
"Leatherique gets sucked into the fibres and expel all other contaminants. I've used nearly 1 litre of Rejuvenator Oil to treat my neglected Alfa seats as the leather just gorged itself on it and expelled so much gunk out of the fibres."
I know the Zaino description sounds similar but there a important differences. All other leather products treat the
surface, regardless of what they claim. Whatever ingredient "penetrates" the leather is minimal. How does something penetrate clear-coated leather? As such, they work best to remove surface grime and condition the surface of
coated leather.
Un-finished leather is a different animal. Any grime, salts from perspiration or oils are driven deep into the fibres by body contact and pressure. Over time they go very deep. Cleaning the surface will only give an
appearance of cleaning. Then when a typical leather conditioner is applied to the surface after 'cleaning' it adds its own oils and whatnot pushing the gunk deeper, and if it has silicone it'll seal in all the below surface grime which will deteriorate the leather fibres further.
Leatherique's method of treating leather is the opposite of what we're used to. You condition/restore first, then clean. The Rejuvinator Oil (RO) uses the principle of displacement to clean the leather, and at the same time conditions. As I've said, I used almost 1 litre on the back seats. It drinks in large quantities of the RO which contains natural collagens and fatliquors that condition and restore/soften the leather. These beneficial ingredients have an affinity to the leather fibres and restore it to its natural state. What cleans the leather is
displacement. As the leather gorges on RO, it dissolves and displaces deeply ingrained contaminants. These rise to the surface and look like a white sticky scum. This can happen quickly or over several days. Heat accelerates this process.
Then you use Prestine Clean (PC) to dissolve the surface scum and wipe clean. Then you repeat this process until the leather stops
drinking. 1 Litre later, portions of my seats are still drinking.

But what was once cardboard hard is now like kid-leather...you just sink into them.
BTW, PC can be used on both coated and non-coated leather, an vinyl. Its a very diluted version of RO, so it still mildly conditions while it cleans.
So as you can see, its a long process on neglected seats and is more than a surface dressing/cleaner, which most others are.
Sorry for the essay, but I'm trying to explain as best as I can the differences. :bigups