Tom, the reason I recommend oil with Surround is because Surround is said to create the perfect environment for mites. But now that you bring the question to my attention I wonder how accurate that is. I don’t manage enough orchards organically to have a wide range of anecdotal evidence on that.
With the pyrethroids, such as Triazicide, I’m almost certain that mite flair ups are encouraged and even possibly whitefly outbreaks, so maybe I should start mixing oil with that when the weather is cool enough (below 90F).
In summer I never mix much more than 1% oil to water.