Hawzah News Agency – Ayatollah Khamenei answers a question pertaining to the rules of the Wuḍū’.
Q: Are the natural oily secretions of the body — that cover the hair and skin — considered a barrier that would prevent water from reaching the skin?
A: It is not considered a barrier unless it is so much that it would prevent water from reaching the skin and the hair.
Source: https://www.leader.ir/en/book/32/Practical-Laws-of-Islam