From what I've noticed it seems like the new smaller ones use plastic tanks and they all are water based only.
Thanks for the input. So would a plastic tank really be a bad thing? Less durable maybe, but I don't plan on dropping huge parts in there from 4' up. The ones from Northern and Amazon are metal, but a little smaller. This will be used for minibike engine parts only. The metal tank models have the pump mounted to the base of the tank while the plastic Harbor Freight one is just suction cupped, allowing it to be moved around. Not sure if that's good or bad.
As for water based fluids, that gives me the advantage of using it in my basement in the winter. However, I don't know how effective water based tank solvents are. If anyone has a brand they prefer that really works, I'd love to hear it.
Seems the pump reliability is the major flaw with all of these, but they don't seem to have very good filtration, so I can see why they might fail. Normally I buy good quality tools but in this case, there isn't an affordable high quality option for such an occasional use item.
Maybe I'd be just as well off with a $5 Rubbermaid storage tub filled with solvent and a parts brush. If anyone else has experience with one of these small units, feel free to provide input. Thx.