I've never been a big fan of mineral spirits in a parts washer.Probably bacause I was always comparing it to the other stuff that was available,(Safety Kleen was one of them).I used a lot of Agitene,parts stores here sold it with no paperwork like some of the others.Three gallons of kerosene and two gallons of naptha worked pretty well,but you had to keep the lid shut on the parts washer or the naptha would evaporate.It still cleaned well,but would leave a residue on the parts once the naptha was gone.I used to use two parts washers,one with old juice in it to pre-wash,and the second one with cleaner stuff in it.The John Deere dealer I worked for years ago did that too.They had a gas bucket/tray outside under a roof,when the heavy muck was taken off the parts then we brought them in to the real parts washer.After a couple of uses you couldn't light that tray off with a torch.
