Brass Petroleum is crude oil.(oil that comes from the ground?) Are you talking about Petroleum Oil, such as the type we use for cars? (S)
I'm not sure I understand your thread..
Are you asking if you can use crude oil (petroleum) on citrus? Toni

Paraffinic oils are made from petroleum, so are likely the same thing. I'm not sure what a "soluble" oil would be, since that's an oxymoron -- if it's soluble in water it cannot be an oil. Emulsifiable, yes. But soluble, no.

I would not use any oil frequently -- they stress the plant too much. But occasionally, to clean up a problem, and as you suggest, in the cool part of the day, yes, that's fine.

Toni,
When I was searching on the net for oil that I can use on citrus, I ran across the name Paraffinic and Petroleum Oils -- both horticultural oils.

Malcolm,
Thanks. I think it was two summers ago that I sprayed the citrus with oil and fried the leaves, lost the leaves and gained some respect for what happens with oil on leaves in high temperatures.