I sprayed mine with neem oil, I didn't dissolve the water and oil well because I didn't add soap, it's kind of repulsive to me because if I wanted chemistry I would take pesticides and fungicides.
I mostly dissolved it in lukewarm water, 30 ml of neem oil to 3 liters of water.
Just watch the foam a little bit because it doesn't dissolve well so you don't spray it on the plants because I did and they damaged my leaf a little where the spilled was, but it was dark so I didn't manage to see it then, everything else went well and I can say it's doing the job.
I sprayed in the evening, but what I read can also be done early in the morning, before sunrise and while the temperatures are still lower, like everything else when spraying, but everything I spray, I spray before evening.
I also read and many people told me that oil-water 1-25 works, but I followed what the manufacturer said and that's what I did, 30 ml for 3 liters of water.
And it also said to add soap, but I just didn't want to.
I couldn't find the oil anywhere, I found it in a pharmacy where they buy medicines for people, but if you find it in an agricultural store, it's sure to already have a solvent in it and you won't need soap to dissolve it better.