Shelf life?

What is the shelf life of thread? I've read and heard that you shouldn't use old thread on a new project, but what about using old thread on old fabric? I have some fabric that I know is from the 70's. Is it ok to use thread from the 70's?

The reason I ask is because I have more thread than I could possibly use in my lifetime. I'm going to try...don't get me wrong! Today I got to sew for quite some time. It felt good!

I actually got some string blocks done! And more started. I have a bunch of foundation squares cut (thanks Carla-from like a year ago) and am going to keep working on that bucket of strings.

I looked on the internet and found a recipe for making my own spray starch 3 tsp of cornstarch and some water (great, I forgot how much) and put it in a spray bottle-on my list to buy next time I'm at the store, and I am going to try to make the blocks without a foundation and see how they turn out.

In the goodies I got last weekend, there were two drawers full of thread like this...

and one plastic box of thread like this.

I am using up the bits and pieces and going to give the empty spools to my son's first grade class. They will be great for sorting, counting, classifying or maybe an art project. I used to teach first grade and loved it when people would save and send in things for the kids to play with and sort.

There are quite a few hand quilting spools here. Either I am going to learn to hand quilt, or find someone who does :)

So, what do you think...how safe is it to use up the thread on the wooden spools? They don't sell it like that anymore so how old do you think it is?

And how do you store your thread? In boxes and buckets in the dark, or on display like this? I have one more thread holder, plus one bobbin holder with about 100 bobbins on it too. Yeah, I have a lot of thread!