With volatile components to evaporate, most likely organics (hence Volatile Organic Compound), it was not a simple gun-oil. Congeal has no common technical meaning, it is a term of kitchen art.
A common recommendation for gun storage is to put it up with your lubricant of choice as you would use at the range for intended firing, but more of it. My gun manuals are consistent in their recommendations of nearly dry for carry (to minimize lint/dirt accumulation), a bit more liberal for lubrication at the range and wet for storage. I use a high pressure grease.