How old can yeast be and still have a chance?

Cleaned out the beer fridge and came across some yeast I had forgotten about. White Labs vials labelled late 2013, early 2014.
Any sense doing a small, low OG starter and hoping to bring one back to life?  A few Mexican Lager, a Kolsch and and Irish.
Thx

In my book, absolutely! I’ve used older, dirtier yeast than that and turned out great beers. Make a starter; give it time; and taste the resulting [edit: starter beer] “beer” for badness and make a decision.

I’ve started up and successfully used a 3 1/2 year old smack pack.  Just start with a small, low gravity (1.020ish) starter and step it up several times.

Is it worth the effort to try? Let’s say you spend 20 min per step + the cost of DME, that to me is more than the cost of a fresh pack. If the yeast is hard to come by or a seasonal strain, I’d do it.

+1

I just hate wasting money. I’d used DME either way so I figure a lower OG try is no big deal. Plus I have no LHBS nearby and I don’t need anything else so the cost to ship fresh yeast is about the same as the yeast itself so I may as well give it a go.
If there was no chance I would order fresh but I also like a challenge.

If getting yeast is though for you, go for it

Flag porter is brewed with yeast salvaged from a ship wreck that was over 100 years old.

If you save some wort from every batch, you don’t need DME.  Just defrost a pre-measured starter wort, boil for a bit, cool it, and pitch the yeast.

How much effort does it take to boil some wort while your cooking dinner or something like that?

Plus, sometimes it is worth the effort to try just cuz.

Definitely be sure to use a very low OG (at most 1.020) and a very small volume.  Maybe 250-350 mL or so?

I did a small 1.020 starter and its alive, did a 2nd 1.5 L with 1.040 and it seemed to ferment out but it seems slow. Little bubbles etc but not a big active krausen. Stopped bubbling so I’m cold crashing and stepping again. Any thoughts on strength?  Stay at 1.040 or go back down to make it easier on the little fellows?

I’d go back down to maybe 1.030.  No need to stress it.  You want lots of healthy yeast.

Ok, will do 75 g of DME in 1L. Should get me pretty close right?  I’ve always been told 10:1 got you about 1.040.

Not that it matters but I have decided to use this for a 1.040 Timothy Taylor clone mashed at 156 so looking for about 3.8 % ABV, the. I can harvest for a bigger brew. Not going to try anything crazy high OG with this one. It’s Wyeast West Yorkshire.