A method for detecting leakage from a disk drive enclosure includes providing a lubricating composition having a lubricating material and a tag material therein. The tag material has a volatility characteristic that is amenable to analysis. The method includes measuring a concentration of the tag material in the vapor phase. By measuring a concentration of the tag material, a leak rate of the lubricating material can be determined. The lubricating composition may include a perfluoropolyether lubricating material and a halogenated sulfur tag material such as SF₆ and/or S₂F₁₀.