mashie said:Not all systems leak so replace when with if.
As for using oil instead of water, well first off it is aweful for conducting heat compared to water. Secondlly, the viscosity of oil will kill all water pumps, and pumps suitable for oil has amost no flow instead so not much good for transfer heat from your blocks.
Just forget the idea, consider it a bad dream or something.
a real nightmare would be a leaking waterloop frying my computer