No damage to turbulator fins?

Low pressure is key with the pressure washer thing. In fact, a garden hose would probably be fine if you can't dial the pressure washer down far enough.

I've got a gallon of in the garage that I'll be using to clean the inside and outside of my used Precision 600.

IF you choose to use an industrial grade cleaner, follow the damn instructions on the concentrations.

As EO2K said, make sure it is a lower pressure. Mine is 3300 psi 3.7 GPM. I put holes in things if not careful. When you use the soap attachment it lowers the pressure dramatically.

Also yes, follow the concentration amount carefully. Super easy to damage aluminum with even Purple Power.