The first mityvac is a MV7201. I have one just like it. There are a few issues I've found with it, but nothing too serious.
First, the hoses are a bit short, so you have to connect two together to reach the bottom of your oil sump.
Second, the way to "conveniently" dump the oil is to remove the plug, which is one of those expansion plugs - lift the handle and the plug diameter is supposed to get smaller. Unfortunately the plug has a tendency to deform into position and takes some work to get out.
Third, the connection for the plastic hose didn't seem very durable, started to leak. That's okay when you're sucking oil, but if you have to remove the oil by air pressure then it's more of a problem.

Mityvac has parts so you can fix it though. I need some of the plastic though and they are god-awful expensive from Mityvac. The fittings are metric. Does anyone know what to order to replace the plastic lines all around the unit? What material are the plastic lines?

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mjk

'84 300SD 119KMi (Liesl der Diesel)
'84 300D 326KMi when the oil left (former parts car)
'82 300SD 253KMi (new parts car)