Body oil stains.. vinyl versus leather versus cloth. Some cracking... how to tell?

[vanhammer]

I have seen armrests in some trucks that i have bought and others i rode in that had a "thick" hard stain from what i assume is body oils compounding over time. The first was on a medium grey cloth in a 93 blazer... i used carpet cleaner and a scrub brush to get it up as best i could.

The second was a 2002 chevy avalanche with dark grey interior. The armrest was either leather or vinyl but it wound up cracking the material because the stain was so hard that it couldnt flex very well... or maybe it dried the material. Or both. Not sure.

The one now is an 07 avalanche with black interior... not sure if leather or vinyl but it has developed a 1/8th in crack and i want to save it if i can. The armrest is actually the console lid... the drivers side of the lids material will not flex much at all (because of the stain i assume) but the passenger side is very soft.

I have noticed this as a common problem on all neglected cars it seems. Or at least it seems like it to me... comments?

My questions:

1. Whats the best method for removing the stain on cloth, leather and vinyl?
2. Will leather conditioners bring the softness back to leather and if so, to what extent? Even if to the point of cracking too?
3. Does the leather conditioners work the same on vinyl?
4. Is there an easy way to tell if you are working on leather versus vinyl "for sure"?
5. Recommeded products for above questions.

Thanks in advance.

[vanhammer]

I guess ill just try the sonax kit.