Wow, I wonder if the Stabil has a different formula now? I had a bottle on the shelf for 3 or 4 years, and never found any crystals in it. I even used it at that point to help unclog a carb on a trail bike because I forgot to add the Stabil to the fuel before storing it. I'll keep a close eye on my newer bottle, though.
As for the diesel fuel additives, Stanadyne is great, but harder to find. Power Service just got pulled from our local Walmart's shelves, supposedly because the EPA said it doesn't meet current specs. But I found it in stock at Napa, and they said they haven't gotten any notices from corporate about having to pull it. I just recently got a bottle of SoyShield from my local Schaeffer rep, so I'm going to try that out.
I recommend that EVERYONE use a diesel lubricity additive from here on out, as the new ULS diesel fuels are so low in lubricity, and have no lubricity additives required to be added back in, that we are going to see more and more damage to diesel engines in time.
So either add diesel additive, or start using a biodiesel blend to protect your engines.