I'm using mineral spirits that you buy in 5 gallon cans. At first I bought the water based one where you mix 50% water and 50% the chemical. It ate the paint right off of the insides of the washer! I took it back to Northern and they gave me a new one since I had bought the washer and the chemical from them, and since using the mineral spirits I have had no problems.

I haven't had the occasion to use it for the past couple of years but am thinking of changing the liquid and starting to use it again.

Don