If a person applies kohl during the day in Ramadaan whilst fasting, that does not invalidate the fast, but if he feels a trace of it in his throat then to be on the safe side he should make up that fast. It is better not to use kohl during the day when fasting.
If a person applies oil or cream to his hair during the day in Ramadaan when fasting, that does not invalidate his fast.
And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and upon his family and companions.