Fluid Extractor

I personally use one to change the oil in my boat's big block. In the best situation you are better off draining fluids whenever possible to get particle sediment from the bottom. Also, if you have a magnetic drain plug you can wipe it clean of debris. It would work fine, but you'll get a cleaner fluid change by draining. It's great for power steering fluid changes. Draw out what's in the reservoir, fill it, run it and repeat drawing the fluid out and refilling a few times to get mostly new fluid in there. ATF is fine to replace PS fluid.

I use the vac all the time for fluid install, but for drain I would have to second with anthony05GT
drain fluids when ever you can.