Oil (Ex): Line of acid 5 ft. long and 1 ft. wide; Fortitude save (DC 12) or suffer from painful blisters. Those affected receive a -2 circumstance modifier to attack rolls for 1 day. Curative magic heals the blisters and removes the penalty.
We could call it sickened instead (though that is a bit more severe)? It didn't have the saving throw originally, but then in the conversion it was a line and not an attack roll.
Oil (Ex): (range increment 5 feet?) Living creatures hit by an oil beetle's oil attack suffer from painful blisters and be sickened for 24 hours. Application of any curative magic, or a DC 15? Heal check will return a sickened character to normal.
"Oil beetles are 3' long giant beetles that sometimes burrow underground."
Hello! Should they not have a burrow speed?