Hiya Stardust, just see this thread tonight. I use lots of Patchouli oil in my oil burner and it is so gunky and sticky and yuk (but smells great!). I have used bread soda too or even a little hand washing powder and hot water and leave it on draining board etc. overnight. Next day it just comes off. I keep a separate kitchen sponge to clean this and it works a treat!
Love Rachel x