عَنْ عَلِيٍّ رَضِيَ اللَّهُ عَنْهُ قَالَ: كُنْتُ رَجُلًا مَذَّاءً فَسَأَلْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ فَقَالَ: ((أَمَّا الْمَنِيُّ فَفِيهِ الْغُسْلُ وَأَمَّا الْمَذِيُّ فَفِيهِ الْوُضُوءُ))
It is narrated from Sayyiduna Ali (may Allah be pleased with him), he says: I used to have a lot of madhiy (pre-seminal fluid), regarding my question about it, the Messenger of Allah (peace and blessings be upon him) said: Ghusl is required for semen, and wudu is required for madhiy.