Coconut oil and chocolate smoothies

We make a variety of flavoured chocolate smoothies, (aka the poor man's truffle). We use a microwave to soften the coconut oil.Originally, wejust softened it enough to whip it to a mashed potato consistency, and it worked quite well, and set fairly quickly.

Then, even though we did not change coconut oil brand, it seemed to be grainier at whipped potato texture and we had to heat it longer, and now, unless it is melted completely, it still has a grainy texture, which shows up as white spots in the finished smoothie. Any suggestions would be appreciated.

I find the coconut oil / butter handles very differently at different times of the year - but we are in Australia. In summer it's very easy to separate from coconut cream and milk as it's liquid, similarly in winter its easy an its hard. There are transitional temperatures where it appears grainy and is like sludge. Maybe your working at some transitional temp. From memory it melts at about 27 degrees centigrade.