Originally Posted by RainyEyes
The only time you would put oil in the barrel is in real steel barrels where acid from your hands can tarnish or cause rust in the gun.
+1. Don't use any stuff such as Hoppers 9 or Gunzilla on airsoft. Those things only help real toys.
P.S If you decide to clean the barrel, make sure hopup is off. Otherwise bucking and sleeve might get damaged.