I have never had mold grow on my comfrey oil, but the first batch I ever made was smelly and "weird" looking after a few days. I put 2 tbsp of white vinegar in it and the smell went away, I did that because I wasn't sure if botulism was an issue and the acid would help.
However, before I make any oil I boil the jar and lid, just like I'm getting ready to can and put the oil in when the jar is hot to sterilize the jar, maybe try that.
Tami
