I am quite handy but I've never bothered to try my own car maintenance. But I want to start with oil changes so I know how. After crawling under my 2008 Subaru Impreza and finding the oil drain plug I noticed that it wasn't simply a normal hex head bolt but rather a "reverse" or "concave" head, I've never seen this before. How am I supposed to remove it, I don't even know what to search for to buy. I tried to find a close photo of something similar as shown below.

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  • standard hex or allen socket not to plug a particular brand bu here is a pic sears.com/craftsman-6-pc-metric-3-8-in-dr/…
    – agentp
    Jun 3, 2017 at 3:06
  • A simple allen key will also work. Saves on buying a set of allen sockets, but that might be a good investment...
    – Solar Mike
    Jun 3, 2017 at 6:26
  • That would be a metric Allen wrench!
    – Moab
    Jun 18, 2017 at 4:30


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