It was narrated from Ibn ‘Umar that the Prophet ﷺ used to put oil on his head when he was in the state of Ihram, but not oil that was perfumed.  

أَنَّ النَّبِيَّ ﷺ كَانَ يَدَّهِنُ رَأْسَهُ بِالزَّيْتِ وَهُوَ مُحْرِمٌ غَيْرَ الْمُقَتَّتِ