I use finely powdered stevia that I've suspended in castor oil to sweeten my balms with right now, and I'm also experimenting with white chocolate chips on the side for fun. I used the chips @ 3% of my formula. The chips just contain cocoa butter, sugar and lecithin, I believe. I've made one batch of lip balm with the chips and so far so good. It's sweet with no grainies (as of yet) I made the balm 2 weeks ago.
A lot of people use stevia because it's in the catagory of 'natural' sweeteners and its also vegan. It's very potent, so only a very small amount is needed to sweeten your balms. You'll know you used too much if your balm tastes bitter. It doesn't dissolve in oil, but you can suspend it in whatever kind of oil you are using in your balm. So far, I've experienced no grainies with it. My stevia powder is
very finely powdered, which I believe is the key. The dry stevia powder I have has absolutely no grittiness to it at all when I rub it between my fingers. It's like fine talcum powder.
I know that some people use an oil infusion of pure, unadulterated sucralose in their balms. Sucralose is the stuff that Splenda is made from, only Splenda has maltodextrin added to it. From what I've read, the unadulterated kind of sucralose is hard to come by. It seems to only be available to those who work in the food industry (unless things have changed and it is available to the general public now, but I haven't kept up with that). I've seen it offered on forums co-ops in the past when someone has been able to get a hold of some. Those that have been able to do so and have used it in their balms say it's great. Like stevia, only a very small amount is needed to sweeten lip balms.
IrishLass