@Bonevader I have read that it’s recommended to use Silicone Oil specifically formulated for hot bath application. However, due to difficulty in obtaining that oil my team went with using Avocado oil for now. Works great! Basically, any oil that has a high smoke point temperature (>200celsius) should be good to use in a roto for decarbing temps.
EDIT: oil degradation and oxidation may vary between oil producers depending on their SOPs for refinement of crude oil and maintaining clarity along with shelf-life stability. Despite that, if your rotovap isn’t too big (<5L) then buying more cooking oil in the case of degradation could still be affordable and gets your rotovap capable of decarb.
@Doyathang THC boiling point at ambient room pressure (@760torr) is 425c
In order to reach THC boiling point at 140c you would have to maintain a vacuum pressure of 0.04 mmHg (40 microns). With the average SPD setup I have used (china-brand turnkey package), including a dewar cold trap, and edwards e2M28 vac pump I see vac levels in the range of 200-500microns. At the lowest of that range (200 microns) it allows me to boil THC at a head temp of about 180c. See the nomograph for this relationship (thc b.p. VS vacuum pressure) here