Diester based synthetic lubricants provide numerous per formance advantages over mineral oils in industrial applica tions. The synthetics not only .permit significant extension of oil drain intervals and application over a wider 'temperature range than mineral oils, but field experience also indicates that synthetic oils develop thicker and stronger films than their mineral oil counterparts. This results from the combination of the diester basestock and appropriate additives. A laboratory

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... tion has been conducted to quantifY the performance advantages of the synthetic oils over mineral oils in hydrodynamic lubrication. The power loss, maximum 139 pad temperature, and oil film thickness in a tilting pad thrust bearing were measured for an ISO VG 32 mineral oil and ISO VG 32 and VG 10 diester based synthetic oils. Results of the tests revealed that the comparable grade mineral and synthetic oils yielded similar bearing power losses and pad tempera tures, while the synthetic product developed significantly thicker films. Relative to the VG 32 mineral oil, the VG 10 synthetic lubricant yielded lower bearing power losses and cooler operation, while developing a slightly thicker film. These laboratory test results confirm the field experience that replacement of mineral oil with a suitable grade synthetic lubricant can yield significant economic and technical benefits, including reduction in bearing power losses, without sacrific ing machine protection.