I spent about 1.5 hours treating my Leather with the Byrons Hyde Food Leather conditioner
My interior was redone using the GAHH seat kits and a hide for dash, door cards, kick,and rear shelf panels.
GAHH's website recommends Byrons and you can buy it there for $30 or on ebay for $15; enough in bottle for 10-12 treatments.
I spent 1 hour last week using a bucket of very, very hot water and a large microfibre towel wrung out to just damp to wipe done all the leather. Water was black; refilled twice.
Today I used the Byron's spraying it 1-2x on a small microfibre towel and wiping down all the leather. I then used a dry microfibre towel to buff.
I let car sit in direct sun for 1hr to warm up leather; did one pass on seats, dash, knee pads, door cards, and rear deck. I did an additional pass on certain areas (windshield posts, tops, a-pillars, doors card bottoms, etc) that were looking dry.
Overall, great result. At first, the leather seems darker and richer. But, it shortly returns to original color and has very, supple, soft, satin/matte hand.
Its water soluble and liquid spray not gel or cream; clearly not oily or greasy or uneven shiny patches as I have noted with Griots, Zaino, Zymol, and other commercial leather conditioners.
It leaves a natural leather scent; more like tannery oil and less like the "artificial leather" smell you get with above.
If you have the GAHH interior, I would highly recommend.