A cheap Lacquer thinner for cleaning guns is fine ( use a plastic bottle that wont melt to squeeze it through the passages of your gun , but dont hook it to a hose and spray it , as lacquer thinner is a BIG VOC product when atomized .

I use a PPG's 330 wax and grease remover and their SX1005 water wipe too , a wax and grease remover will NOT remove any water soluble contaminate on the car , ( like water sanding sludge , soap used in water bucket from water sanding )
Use the 330 first then the SX1005 you'll be amazed how much more crud will be on your rags even after cleaning with a wax and grease remover !!

JUst be safe with these products , get a box of Nitrile gloves to wear when using these products . It will save on your skin