hafrogman
Adventurer
If the rats prove to hard to deal with without oil, I would be remiss as a DM to not point out that the keep's store room is at most a turn or two away back down the tunnel. All you have to do is get Escobar to open the gate again, admitting that you were thwarted by ROPNS*.
*Rodents of Perfectly Normal Size
*Rodents of Perfectly Normal Size