What do you use to detect leaks?

[HavocX]

I have always used a little soapy water when checking my airguns for leaks but cannot stand the mess it makes, constantly having to wipe areas down and in some cases disassembling parts of the gun to clean the soap/water before it causes rust.
Is there a oil that would be better suited?

 

[Ziabeam]

Tread very lightly here.
The wrong oil could be entertaining at best, disastrous at worst.
Oils that are not impervious to dieseling could cause an explosion down the road if they creep into the wrong places..