how to clean the nylon shell on down jacket ?

So I picked up a nice down jacket for a song. Its been gently used. There is a very slight discoloration on the front. I would rather not wash the whole thing. Is there another way to clean a 6x6 in patch? Honestly, its a backpacking jacket and Im not too concerned about how it looks, but would like it as clean as possible....if possible

Thanks for any advice

Cheers !!

Since it's just a small spot, I'd suggest K-12. It's for taking stains out of carpets. Be sure to try it on a small area that isn't critical first. Never know how a particular fabric and cleaner might interact.

I'd wash the whole thing, using down soap (see the Western Mountaineering website for instructions on washing sleeping bags for recommendations). It will fluff up the insulation, too. Besides, if there's a stain on the shell, part of it has undoubtedly gone inside!

I would use something like this-
http://www.nikwax.com/en-us/products/productdetail.php?productid=266&activityid=1