Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Mityvac 7400: it sucks because it doesn't suck

I bought this product for use on a BMW 330i. I tested it in a sink to be sure it would work (no problems). When I attempted to use it to vacuum the oil, it hardly sucked out more than a cup of oil. I warmed up the engine (who knows if it wasn't warm enough?). The hose was so short I had to hold the unit on top of the engine (very awkward to try to pump that way). I tried both tubes thinking maybe one or the other would produce a better result; neither was better than the other. In the end I just packed the unit up and sent it back. I also found it nearly impossible to remove that plug thing that joins the hose to the unit; I'm guessing dumping used oil with that plug blocking the spout would have been nightmarish as well. I contacted the Customer Service and it took 3 days for them to contact me (pretty poor, IMO).