8 XXX : leather shoes

Ruined my boots working in an oil shop. Any idea how to clean them ? Most Google returns are for hard shell leather.

imgur.com category @MRNOEXISTER

How to repair the cracks on this leather shoe?

imgur.com category @l57y

Leather or canvas for these shoes? Also, would the leather ones look good with jeans?

imgur.com category @Boxcart100

Advice on how to get this leather back to new?

imgur.com category @jatspaceman

Anyone know what brand these are? The only marker is the logo embossed in the leather (ms paint rendition)

imgur.com category @Pigeon-Toes

My handmade (self-made) leather chucks :-)

imgur.com category @H3BB3

Leather shoes

imgur.com category @mammary_shaman