There are many reasons for NOT using grease-base polishes for cleaning parts to be inserted into the interior of high vacuum systems, as is so commonly done in electron microscopy laboratories. This matter is discussed in some detail in my book Vacuum Methods in Electron Microscopy. (Portland Press, Ashgate Publishers, 800-535-9544), pp. 69-74.
Basically, one principal reason for cleaning most parts in the first place is to remove hydrocarbon materials from their surfaces, and so it makes no sense at all to use a greasy material to do the job.This is the equivalent of taking a bath in a mud puddle. Then, it becomes necessary to use ‘toxic’ organic solvents to remove the grease-base compounds, which in turn generates expensive and annoying procedures for the use and disposal of the solvents. In addition, the grease and abrasive materials are likely to get embedded in cracks and crevices of the parts on which they are used, and since they often are not readily soluble they may not be completely removed, whereupon they will subsequently act as a persistent source of contamination inside the vacuum system.