312 higher cont act stresses will create additional wear which will react and consume available lead naphthenate  making it unavailable to create a protective tribofilm. From this research, the following conclusions were  found.  

SRV Oscillatory sliding experiments :  - At 20°C boundary film testing in a pure oscillatory sliding mode, it was shown that samples with  lead naphthenate used as an anti -wear additive outperformed neat MAC samples in all  experiments. Under vacuum conditions, the samples with lead naphthenate offered twice the wear  protection with 440C performing the best under vacuum conditions.   - At 75°C in pure oscillatory sliding testing, all experiments performed better on 52100 steel  than  440C which vacuum tests showing significant wear reduction .   - At 75°C  in atmospheric conditions , the neat MAC oil outperformed the samples with  lead on 52100  steel with additional concentration of lead increasing the wear rate. Under vacuum, the addition of  lead reduced the wear rate.   - At both 20°C and 75°C in boundary film testing in a pure oscillatory sliding mode on 440C, samples  with lead offered up to twice the wear protection over the neat samples in a vacuum environment.   - Lead Naphthenate had better anti -wear performance at lower temperatures and increasing the  amount of lead directly reduced the wear rate, apart from 52100 at 75°C and atmospheric  conditions . At higher temperatures the wear rate was almost double for the highest lead loading  across all tests.  

MTM mixed rolling/sliding experiments :  - At 50°C in the mixed lubrication counter -rotation wear test, lead naphthenate offered three times  the wear protection when in a 3% concentration and eleven times the protection for 5% lead  compared to the neat MAC fluid. The comparative anti -wear additiv es of TPP produced 20%  greater wear and TCP had 3.5 times the wear protection compared to the neat MAC fluid.   - At 50°C in the boundary lubrication counter -rotation wear test, lead naphthenate offered three times  the wear protection when in a 3% concentration and nine times the protection for 5% lead compared  to the neat MAC fluid. The comparative anti -wear additives of TPP reduced wear by five times and  TCP had six times the wear protection compared to the neat MAC fluid.   - At 150°C in the mixed lubrication counter -rotation wear test, lead naphthenate offered five times  the wear protection when in a 3% concentration and twenty times the protection for 5% lead  compared to the neat MAC fluid. The comparative anti -wear additives of TPP reduced wear by six  times and TCP had two times the wear protection compared to the neat MAC fluid.   - At 150°C in the boundary lubrication counter -rotation wear test, lead naphthenate offered three and  a half times the wear protection when in a 3% concentration and twelve times the protection for 5%  lead compared to the neat MAC fluid. The comparative anti -wear additives of TPP reduced wear  by two times and TCP had three times the wear protection compared to the neat MAC fluid.   - There appears to be is a transition point between 3% and 5% lead naphthenate where the available  lead can react with both the surface and worn metal to create a strong lead anti -wear tribofilm. This  tribofilm that is created is between 2- 4µm thick and while it will cause an overall increase in friction  at the surface, the wear of the contact is greatly reduced.   - Lead Naphthenate had better anti -wear performance at high temperatures and increasing the  amou nt of lead directly reduced the wear rate.  

SOT and Vacuum Bearing Tests:   - In both rolling element tests (SOT thrust bearing simulation and ACBB testing), the neat MAC fluid  or grease outperformed all samples with anti -wear additives.   - The TPP additive performed the best of addatives  tested in rolling element tests.   - The lead additives performed very poorly in the vacuum bearing tests with greater than forty times  the wear of the neat MAC fluid for the oils and twelve to fifteen times the wear in the greases. In  the SOT testing, lead additives  reduced the relative lifetime by 50- 75%.