I gravity drained the oil into the gallon jug just to show how it works. Normally I take the tank to the town recycling facility. All I need is a horizontal plank so the tank can stand upright and let it rip. Here's also where the 3/4 i.d. hose size comes in handy (as opposed to 3/8 i.d.), it gravity drains pretty fast without adding pressure (who wants extra complexity?). I estimate with cold oil it will gravity drain 4 gallons in a few minutes. The vacuum fitting is a gutted Schrader valve silver soldered to the tank with a metal stem cap to keep oil from spilling during storage/transport as well as an air inlet while draining.
Here's a really nice DIY funnel. I made it for the VW where the valve cover has a plastic guard under the filler hole which prevents use a regular funnel without having to holding it in place with one hand which makes the job very clumpsy. This one is made from a Simply Orange container and fits tight in the filler hole. The mouth is slightly too big but a file will reduce it in diameter so it fits tight (make it a taper when you file). It fits just as well in the Mercedes valve cover.
Don't throw the other half out! It serves as a funnel storage.
