I used TruckerCo Cream Latex Sealant. I bought it instead of Stan's because it was a lot cheaper (like $16 for a liter, including a syringe). It seems to work ok, but now that it's gone (100ml ea. into 6 tires (3 tubeless, 3 tubes), 200ml more to re-do two tires that suffered trauma, and 200ml lost in the learning process) I plan to mix up some homebrew and switch to that.