I’ve found it an improvement to the method to NOT use heat to help dissolve the pellets.
Now, without using benzyl alcohol and without using heat, it is somewhat of a pain to get the pellets to dissolve in the oil. It can be done however.
A fresh-out-of-the-wrapper large syringe such as a 23 gauge can be used, with the plastic protector of the needle still in place, as a crushing tool, reaching down into the vial through the oil to crush the pellets. Absolute complete crushing won’t take place in any reasonable time, but a fairly fine powder can be achieved in reasonable time. Other implements if sterilized would be fine also: this is just an example implement that happens to be a suitable size.
A sonicator, e.g. jewelry cleaning sonicator, will help a great deal. Actually I have two sonicators, one a heavy-duty one that can be set for half an hour at a time, and the other a light-duty deal that runs only 5 minutes at a time. In the past, the heavy-duty one was quite suitable for this sort of task, requiring only a few hours of cycling. For some reason however I cannot now find it, and so most recently I had to use the light-duty one. Very many total hours of sonication was needed, along with lots of shaking and several days time. But eventually there was only filler remaining, the formula being at a planned 60 mg/mL.
50 mg/mL would have been easier.
Why do this?
Because it turns out that the heating phase causes much more of the brownish material that gloms filters to go into solution, and remains in solution even after cooling.
By avoiding heat, filtration into final usage vials (in contrast from the original large dissolution vial) is many times easier. If the preparation is made a few weeks in advance, all the better for filtration, but this stuff filters better even 1 day after having been dissolved than heated stuff does a month after having been dissolved.
Benzyl alcohol, 1 or 2%, can be added to each usage vial after filtration.