A Modified Thin-Film Oxygen Uptake Test (TFOUT) for the Evaluation of Lubricant Stability in ASTM Sequence IIIE Test

A modified thin-film oxygen uptake test (MTFOUT) has been developed for use with oils for the ASTM Sequence IIIE test.

The thin-film oxygen uptake test (ASTM D4742) was originally developed to evaluate the oxidation stability of automotive crankcase lubricants under conditions similar to ASTM engine sequence IIID test. The test utilized fuel fractions and mixed metals catalysts to simulate the chemical environments in the engine test. Results on reference oils from TFOUT have been shown to agree with those obtained from the ASTM IIID sequence test.

Recently, ASTM Sequence IIIE test was developed to replace the IIID. The IIIE defines a new oil category having improved performance in oxidation, wear and deposits. The oxidation severity of IIIE is increased by using smaller oil charge and increased blow-by to oil charge ratio.

There are two technical issues with TFOUT: effectiveness in simulating IIIE conditions and the ability to rank oils containing copper inhibitors with oils that do not. The metals catalyst was reformulated and the fuel catalyst was modified. The new catalyst package appears to be effective in simulating IIIE conditions on a series of reference oils. Validation of the modified TFOUT awaits further user experience.