So I spent the last half hour or so cleaning a bunch of bearings, put a, maybe, 3-4 year old drop of YYJ thin lube lube in each, and now they’re all responsive. They weren’t like that before, so did I just screw up cleaning, or is it even possible that it’s the lube’s fault?
Edit: Problem solved, too much lube. What a hassle
How large was the drop of lube? You may have put too much in.
Expire? Not really. It would have nothing to do with the responsiveness of your yoyo. You probably just put too much in. Common mistake.
I have some Yomega lube that’s over 15 years old and it’s just the same as when I bought it.
I probably put too much then, only 1 drop, but I guess the drop was too large
Yeah. All you need is a drop the size of a pin head.
If you had the shields on, then 1 drop is way too much. More like a quarter drop would be more than sufficient.
If you had the shields off, a drop is the equivalent of handing a cement block to a drowning person. Dip a needle in the lube, touch that tiny drop to a ball in the bearing and spin to work in.
Go clean your bearings again or play them until they go unresponsive again.
It’s oil. I don’t think oil expires ever. Like water.
Water can expire.
I had an “old” sealed bottle laying around and I tried it a few weeks ago. It was past the “best when used by” date. Let’s just say it wasn’t the best it could be.
perhaps if the water had additives, but otherwise water should not “expire”. it is bonded hydrogen and oxygen.
Water is generally run over some sort of mineral material to give it a little bit of “something something”. Pure water generally isn’t want people want. We seem to want something more than just pure dihydrogen oxide in our beverage.
I wasn’t saying the water was undrinkable, but it just didn’t have the best of flavor.
Chemicals will leech in through the bottle, chlorine will dissipate out, dust will pass in, rare earth metals will settle… It’s always better to have freshly filtered water. 
Water (as in, not pure H2O) goes flat and stale for sure.
Oil will eventually become more viscous. But in a small sealed bottle? Over the period of not likely more than a year or two? Not gonna happen.
The culprit here is too much oil. Even when I use the pin method, I sometimes end up with enough that it needs to be broken in with 20 mins of play and lots of gyro flops. 
I find 10-ball bearings are more sensitive, too. The same amount on an 8-ball doesn’t seem to be as much of a problem. I’ve never analysed why that should be or if it’s just a coincidence.
Me, I usually just put on a drop, EXPECT it to be responsive at first, and break it in. If I put in so little that it’s totally unresponsive right after lubing, I don’t feel like there was any point.