I love HO sunflower! Walmart sells it by the gallon and it lasts me for forever. I add .1% vitamin E to it when I open and also keep it in the fridge just as a precaution, however. I just finished a bottle that I opened over a year ago and it was still fine. I use hemp in my shampoo bars at 5% to help lower the chances of DOS. So far there hasn't been any, but they don't sit around long lol. I keep my hemp in the freezer and squeeze out as much air as possible after I use it. I also add vitamin E to it. Avocado was mentioned, but I haven't noticed it causing DOS. I make a bar with 20% and haven't added any vitamin E to it and I've never had one of those bars go rancid.. Hopefully I didn't just jinx myself lol.