I don't use liquid fabric softeners and most service techs will say not to use it, it's the worst thing you can do to your clothes(especially 100% polyester) and washing machine(clogs up everything).

As for shelf life, here's an article:

http://laundry.about.com/od/laundryroom/f/faqdetexpiratio.htm

Only buy what you can use in a six month period and it's probably smart to keep powder in a zip-lock baggy or air-tight container.

Gosh I hope powdered detergent doesn't go bad. I've had a bulk thing of it for at least 5 years and I'm not even halfway through it! (no kids and my husband uses cold water liquid stuff)

EDIT

This post was edited by moviegeek on Mon, Jan 5, 15 at 20:57

Eek, maybe time to get of that huge box of Tide then lol. It has reached the rock excavating point.

I've never known detergents to "go bad" in the classic sense. Powders could clump and liquids could separate in time.

I've got a box of the long gone Ivory Flakes in my laundry room - probably from the 60's. It's pretty much like dried coconut now, but still smells like Ivory and raises a mild subs when swished around. I use it every once in a while to wash/soak knit winter hats and mittens.