because his leather had not turned into cast iron like mine
I just got my car a few months ago, and was amazed at how hardened the leather was. It ain't that way any more. You need about a quart of neatsfoot oil, and about 3 days that you are not going to drive the car, nut you will be amazed at how soft this can make the seats again.

Neatfoot oil is what we use on saddles to keep them looking new, trust me, if this stuff can keep a saddle soft in the conditions it has to endure , it will do wonders for your seats. Unlike other products, this stuff soaks right into the pores of the leather, but on coated seats like in the car, you have to give it time. Depending on what color interior you have, it will darken the seats a bit (perfect if you have black) but this will mellow in about a week.

You basically put it on with an applicator, (I use one of those dishwashing things that you put soap in the handle) and let it sit for 2-3 days in a cool place. Buff off any left on the surface ( I doubt there will be any) and you are good to go.

This works much better than any of the other "conditioners" I have seen out there thart just treat the outer surface of the seats, and don't do anything to keep the interior structure of the leather supple.