Here are some simple rules to follow regarding the use of oil during calibration of precision gages.

 ·       Micrometer-

o      USE NO OIL during the normal calibration process. Oil may cause any residual dirt in the threads to create a "mud" like substance which can add wear to the gage and may also cause the gage to stick or completely stop working.

o      If you disassemble the micrometer and totally clean the working parts, then you should oil the threads with minimal oil to prevent rust and make a smooth working gage.

·       Indicator-

o      It is never acceptable to oil the stem on an indicator. Many people, I have learned, believe that a shot of oil on the stem and worked into the indicator will keep it working freely. Quite the opposite is true. Indicators oiled in this way will become sticky and unrepeatable as the result of oil "clogging" the spring mechanism.

o      The only acceptable oiling to an indicator is a very small drop applied to the inside assemblies where the stems of gears pass through the metal holders. Gently work the oil into the gage and wipe away any residual excess oil. It is recommended even then that oil only be applied if the indicator has been fully cleaned.

More often than not, as a result of the environment in which they are used or stored, gages are exposed to excessive oil . Typically I would expect cleaning, not oiling, to be the action necessary on these gages.