I am an amature, but my experience has been that I thin Rustoleum with acetone and cleaned the gun with acetone. I like acetone because it is a solvent I can use in many applications.

The Wilton vise above was painted with Rustoleum thinned with acetone. I may have added a bit of mineral spirits as well. I mixed white and green in an attempt to get Wilton Green. It didn't work. I got minty green.
I also spray with 2k primers, base color and clear coat and clean with acetone.