This billet oil cap from Perrin will keep oil in your engine with a bit of style. You will need to move over your factory O-ring or get a 

CAUTION!  The aluminum cap will retain engine heat, so use gloves if the engine is hot.  Or just wait a few minutes for the cap to cool down before grabbing it with your tender hands. 

Choose from red, black, or neon yellow color.

Fits all 2002-2014 Subaru WRX, 2004 STI, 2005-2009 Legacy GT/Outback XT, and 2004-2013 Forester XT.  Most other EJ-powered cars, too.