Mixing Gear Oil?

[bhayes1]

Cleaning out my garage and have a few different quart sized gear oil bottles that very in weight and synthetic and non synthetic 75w 90 and 80w 90. Would you mix up this cocktail and put it in your axle? I know I've read on some of the bottles "not compatible" but I'm thinking those are the lawyers talking and doing some CYA.

Not a huge deal to buy new and all the same but I know the chances of me using these remnant bottles are not likely and would hate to waste them.

If your against it, what's the main reason? I'm curious more than anything.