Avocado oil as a moisturizer and make up remover

Hello! Since I found your webite, I stopped believing the “all natural” nonsense. However, my skin is acne prone and I have found that nothing works better on it than avocado oil. Commercial moisturizers make it look good initially but then later it gets dry. No such problems with avocado oil, it is the perfect base for BB cream and the perfect make up remover. It’s so easy to remove mascara, eyeliner and BB cream using this oil only. I also dilute some tea tree oil in it and it further helps my acne. But I don’t use any preservatives and I’m beginning to wonder if any damage is possible if the oil goes rancid. Also, I’m not sure how to tell it is rancid and how to preserve it. What is your opinion?