Lexol conditioner is white, but it is very thin, almost watery. If you were to put it on a cloth and then wipe it on your seats, I doubt that it would leave any white residue. Be sure to buff it off as per the instructions. Lexol cleaner is not something I have ever used, so I'm no help with it.
Right now, I am trying a Woolite solution for cleaning my leather and vinyl. Mixed at a ratio of 6 parts water to 1 part Woolite. This mixture has been discussed on a couple of detailing and boating boards, so I thought I would give it a try. Too early for any opinions just yet.