There is no such thing as a "moly build up". Moly either goes into the asperities and crystalline structure of the metal surface, or it stays suspended in the base lubricant. After a metal surface is "moly conditioned", you will notice during oil analysis that the moly additive level won't be as low as it was upon the first application. This is due to the plating action that occured during the intial contact of moly and that surface, once plated it just passes by in the suspended state.

Note: Graphite and many other metallic materials often used in some other lubricating applications are less suitable.  Graphite is a carbon compound and use of a graphite lubricant can contribute to a faster erosion. When two different metals such as copper and iron alloy, interface in the presence of atmospheric moisture and  excellent conductor, (like carbon graphite), galvanic electrical currents are to some degree produced, resulting in metallic oxidation or corrosion and pitting. The automotive industry does not add graphite to oils where heavy PSI loads are encountered in conjunction with higher temperatures.

The relatively hard carbon graphite particles may have an abrasive effect in environments of high heat and pressure. Molybdenum Disulfide is ideal for these high temperature-high pressure applications. MoS2 will survive pressure into the neighborhood of a half million PSI and two thousand degrees F. in an oxygen depleted environment with practically no corrosion and erosion. MoS2 is relatively soft and is not corrosive and non-abrasive.
 

In microphotograph Figure 2, we see a clean, highly polished surface. It is being covered with particles of powdered MoS2 which adheres with burnishing on impacting to the metallic surface. Notice that the powdered moly invades and fills the valleys to the extent that it forms a buffering coating over the tops of the mountainous asperities. The general thickness of dynamic films of powdered MoS2 is in the area of l to 4 microns,(l to4 one millionths of 1meter) as measured by interferometry techniques. The use in bearings impacting moly particles over a metallic area achieves a fairly uniform coating over a short period of time.

In comparison, if that same polished metallic field sprayed with a soluble moly suspended in a lubricant (as in an aerosol application or motor oils), that metallic area would be completely and uniformly coated. Most bonded moly applications generally form a film thickness from 0.0005” to 0.001” (5/10,000” to 1/1,000”).
 

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