Does anyone have one of these Harbor Freight air powered oil extractors? If so, does it work OK? We already have a hand-powered extractor, but it can mean a lot of pumping if you're pulling out several gallons.

http://www.harborfreight.com/6-1-4-quarter-gallon-oil-extractor-46149.html

As HF often does with their items, here's the OM for the extractor. Nice to read these before buying.

http://manuals.harborfreight.com/manuals/46000-46999/46149.pdf

Also, just how does this thing utilize line air to create a vacuum inside the tank? I assume some kind of venturi system?

Thanks