I have never used any sort of special oils/creams/lotions/potions/etc on either one of my boys' penii. As infants, I would wash their whole body, running the soap/rag over their penis just like I did their butt. As children, I taught them to run the soap/rag over their whole body. I have talked about them retracting and rinsing with water (no soap, ever), and how they will need to do that when they are older and able to retract themselves. But it's really not an issue, and they are perfectly fine.