I've been very happy with a parts cleaner called "Next Generation" I buy at the local Advance Auto Parts store. (Western Auto's new "persona"). It went up recently from about $33 to $47 for a 5 gallon can, so it may seem a bit pricey. It seems similar to what they use in Safety Klean (SK) washers. In fact, I use mine in an old SK unit that was abandoned in an old bike shop. You can buy recirculating washers in various sizes. Advanced sells one for around $100 IIRC, and some tool stores sell small ones for as low as $50. These are nice with the sovent pumped out like a faucet through a stiff cleaning brush. The googy stuff sinks to the bottom of the parts cleaners sump.
Of course, shops who rent SK washers get the bonus of environmentally responsible disposal of the old stuff. I'm still looking into that, but for now the sluge is sitting in a previous 5 gallon of the cleaner.
Mark (Nitrile-Gloved) Hoffman,
New Britain, CT