Does the risk of lumps and clots reduces when moving from acrylic to oil paints?
Well, oil paints will be smoother, yes, but you need to know a few things about how it all works, or you will make mistakes.

Oil paint from Van Gogh uses linseed oil. To make a wash, you would add thinner, classically turpentine. The thinner will dry the oil faster, and probably be more like watercolors. Poppyseed is a slow drying oil, and will eventually yellow to some degree, but less than linseed. The finest oil to use is food grade cold pressed almond oil, it makes paint buttery. But don’t eat paint!

If you add thinner, the paint is lean. If you add oil it is fat. You want to make sure that the layers dry consecutively, so you would paint fat over lean. If you don’t, you will face cracking at some point in the not too distant future.

If you want the paint to dry in a matter of days instead of weeks or months, you can purchase a drying agent commonly known as a Japan drier or more technically, a saponifier. Don’t use much and mix it well with the paint. This will generally add a slight blue to your tint and depending on the brand it will make it glossy. I like to use it when glazing, because glazing takes weeks (or even months) to do in the traditional fashion, and the glossy nature is expected.

Don’t get the paint or thinner on your skin, always ventilate while you are painting and keep small children and pets away from your paint.