Rejuvenate Vinyl
 

Working on an old Schwinn with a Mesinger saddle, the vinyl isn't too bad, it isn't cracked or anything but it does feel "dry" is there a way to bring the vinyl back to life? thanks.

I've used dish soap in the past. My concern is that the dish soap might be too aggressive and take of some of the white paint on the seat. I just learned recently about using a mix of Woolite and water. 5 parts water to one part Woolite. Seems like it might be gentler and leave more white paint on the seat while still cleaning pretty good.

Try Armor All.

303 Aerospace protectant, really quality stuff.

+1 on that 303 is the best as far as I am concerned and not that pricey.
Best, Ben

I remember hearing about 303 for my pop up camper parts, can't believe I didn't remember, thanks for the reminder!

LOL, I came across it for taking care of the vinyl roof on my Miata.

Many swear by the 303 but I have had good results with Vinylex (by the folks who make Lexol for leather). I'd avoid any of the products that add slippery-ness (from emulsified silicone for example). Vinylex doesn't do that at least not much, IMO.