What is a "seeking" fluid?

Mechanical Engineering general discussion Pipelines, Piping & Fluid Mechanics
#1

I have been told that fluids like silicone polymer based heat transfer fluids (e.g. Syltherm XLT) have a high propensity to leak and the phrase “seeking fluid” is used. I’m having difficulty finding this phrase mentioned in vendor documents or, more broadly, what makes some liquids more likely to leak through certain connection types.

What properties make some liquids more likely to leak (e.g. surface tension, viscosity) that make certain liquids “seeking fluids”?

#2

I’ve seen “seeking fluid” used when using a liquid for gas leak detection. It usually bubbles and/or foams making it easier to see the gas leak.

Low viscosity and low surface tension liquids tend to leak easier.