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.

[kwmech]

I mix it up all the time, not going to hurt a thing in a diff or older style manual trans like a 465 or a 420. Any upside down bottle drippings after that I mix in with my chain saw bar oil. Nothing goes to waste

[D13]

I might throw it in a old tired axle but not in anything I was planning to drive 100K miles, or keep for a long time. I might use that mix in my farm truck where it's all worn out and goes 10mph max. Synthetic and mineral oils themselves are not a big deal, nor is the weight. The big difference is the additive packages. Modern additives are different than older versions, and the additives in a synthetic are even more different.
When I open a diff its either its 50k oil change or because it needs work and I'm already going to spend some bucks. For the extra $15-20 I'll just put in new and not worry about it.