I have a parts washer I picked up a while back. Haven't used it yet because I have the same question as the OP. But my concerns were having to do with flammability, cost, odors, etc. but particularly, can these things be a fire hazard? What about the pump itself causing a spark, or static electricity, etc? I do recall that these parts washers have an automatic means of shutting the lid if exposed to flame or heat.