A MODIFIED THIN-FILM OXYGEN-UPTAKE TEST (TFOUT) FOR LUBRICANT OXIDATIVE STABILITY STUDY

The thin-film oxygen uptake test (TFOUT) is a laboratory bench test de veloped to measure the oxidation stability of lubricants. It was origi nally developed to monitor the batch to batch variation of re-refined lubricating basestocks under the Recycled Oil Program which was mandat ed by the U.S. Congress under RCRA. A catalyst package was developed f or the TFOUT test to simulate the key chemical reactions encountered i n the IIID engine test As the engine test continues to evolve, the Seq uence IIIE test was introduced and the chemistry changed. A new cataly st package for IIIE was developed and made available in 1991. The pack age contains oxidized-nitrated fuel fraction, a pure nitro-compound, w ater and a mixture of metal catalysts. User feedback suggested a poten tial antagonistic effect between the pure nitrocompounds and same amin e antioxidants contained in some lubricant formulations. At the same t ime, the engine test reference oils used in the original IIIE correlat ion study were changed to reflect some recent technology Bench test co rrelation study based on these new oils suggested some loss of correla tion. This paper describes the successful development of a new catalys t package that circumvents these problems.