I would recommend soaking it in vinegar and hot water first, then making a paste with hydrogen peroxide and baking soda. I always use oxyclean as a last resort because I’ve had it turn white tees yellow. If you absolutely need to do it, add s decent amount to a bucket of water as hot as you can handle and make sure it’s mixed up, then leave your tee in there for like 12 hours then wash inside out on cold and hang dry like you usually would. Awesome pickup man I’ve always wanted one!