Oiling oily hair is generally not recommended. Applying oil to an oily scalp can further clog pores and make your hair appear even greasier.
While some people may find that oiling their scalp helps to absorb excess sebum, it's important to note that oiling is not a one-size-fits-all solution and can worsen the problem for others. If you have oily hair and an oily scalp, it's best to avoid oiling and try other methods to manage your scalp's oil production, such as using a clarifying shampoo or a scalp treatment.
If you have dry hair and an oily scalp, oiling will likely not be beneficial as it can contribute to scalp oiliness. It is generally better to focus on nourishing dry hair with deep conditioners and moisturizing products.