Wan Wen walnut belongs to woody fruit, which needs regular maintenance, and oiling is an important step in the maintenance method of Wan Wen walnut. Not all Wan Wen walnuts need oiling, so how to judge whether Wan Wen walnuts should be oiled? Put the Wan Wen walnut in your palm and play with it. After a period of time, observe whether there is oil. If it is oily, it means it doesn't need oiling; if it is dry, it means it needs oiling. The method of oiling is: first drop a drop of olive oil on the palm of your hand, and then play with walnuts with your hands. Evenly apply olive oil to the whole body of walnuts until the palm of your hand is hot.