There is one spike lavender oil for thinning your paint for underpainting; very expensive and VERY strong oder. I can't handle having it in my studio although I love the smell at first. I heard that if you let it sit outside (cover with a paper towel to keep the bugs out) the smell will dissipate some.
There is also a lavender oil for cleaning your brushes; less expensive.
The clove oil is fantastic for keeping paint from drying out in a closed container. I got a plastic box with a snap on lid that my palette fits in. A felt pad that go under chair legs stuck inside the lid (or use a cotton ball) with a few drops of clove oil from health store or grocery store. Don't mix with paint. I never throw away paint.