What product to deep clean leather?

[funcrew]

If you want the Leatherique or Obenauf's to soak in, you will need to take the hard, slick patina off the seats. You can use acetone with steel wool like I did, and some of the color will come off, or acetone with rags, and hopefully less color loss. After that, the un-gunked leather will soak up as many applications of the better liquid-money conditioners as you want to pay for. Makes your car stink for months if you use a lot, but the seats feel nice. Use a gentle cleaner, such as Leatherique pristine-clean or 1:10 woolite:water after the final application of oil, or the seats will become sticky.

Also - I found out my front sports seats were fake leather this way - they wouldn't absorb the Obenauf's, and only then did I notice that the little cracked spots had cloth fiber showing inside. The rears were real leather. What's up with that?

[funcrew]

Update - In the process of de-gunking and softening my leather seats with Obenauf's oil, I discovered that my back seat was leather, but the fronts are fake leather, whatever that's called in the E30 world. Anyway, I lost a lot of dye (this was expected) in the leather rears, and the front fake leather bolsters are severely spider-web cracked, so here goes:

Q: I was going to try leather crack filler in the spider-webbed fake leather bolsters. Has anybody tried that, or can suggest a different filler?

Q: I want the color to match front & rear, so I think that means a spray can of vinyl/leather colorant to do both materials. Will this damage the leather?

Q: Should I attempt to re-color the sport seat backs while I'm at it?

BTW All seats are tan, and will be re-dyed that same color.

I'm open to all suggestions. Let me know if I left out any information needed for a plan forward.

EDIT: Plan B would be to spray color the fake leather fronts, and use water-based leather dye for the rears. This would make the rears come out cushier, but the color would not match the fronts. Not sure which combo would be better overall.