What oil one in Ihram may apply to his head

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.

حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ فَرْقَدٍ السَّبَخِيِّ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ ﷺ كَانَ يَدَّهِنُ رَأْسَهُ بِالزَّيْتِ وَهُوَ مُحْرِمٌ غَيْرَ الْمُقَتَّتِ .