I have been reading up on horticultural oils for the last couple of hours out of curiosity. Seems like most "horticultural oils" are now highly refined and are considered safe for year-round use. So the term "dormant oil" does not now apparently refer to oils safe only for application during dormancy, but for ANY oil applied during dormancy. Unfortunately I used some horticultural oil last summer on my trees, thinking it would be safe, and though it had zero impact on most of my trees, it burned my Japanese maples and my quinces. So I assumed I was at fault for my application timing... not that the product was.
So I would only say "proceed with caution".
Here's a quote to remember:
Summer or All Season oils are a lighter version of dormant oil that could be applied to plants during the growing season. You still need to use caution when applying summer oil. Oil treated plants will burn in the hot sun and many plants can’t handle oil at all.