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Savant Labs
A World of Lubrication Understanding®

Thermo-oxidation Engine Oil Simulation Test Overview

A key component to automotive engine performance and longevity is the ability of lubricants to resist varnish and deposit formation at operating temperatures. As the number of new base stocks and additives increase to meet more demanding oil specifications, the need for accurate, efficient bench tests that correlate with engine and turbocharger performance have become essential. 


Two Thermo-oxidation Engine Oil Simulation Tests have been developed to reduce the need for increasingly erratic, costly and difficult engine tests in determining the deposit-forming tendencies of engine oils.    

These two TEOST® methods have shown good correlation with both field experience and existing engine tests. TEOST® 33C was developed to simulate deposit formation found in the turbocharger and was correlated to existing field data while the TEOST MHT® (Moderately High Temperature) very closely correlates with the Peugeot TU3M piston ring-belt deposit test. 

 One of the most useful tools in method development is the ability to examine key variables systemically. 

The TEOST® tests have been found to correlate with actual engine oil performance. Moreover, as engines are modified the tests are well suited to maintain good correlation by ease in modifying variables, such as time, temperature, sample size, and catalyst load to predict how changes in engine oil formulation could affect deposit formation.   

 As automotive engines become smaller and required to give more power and fuel efficiency, the thermal stress on the engine oil will continue to increase. These more challenging conditions have opened the way for a new generation of base stocks and additive packages that can offer high-temperature oxidative resistance to meet these conditions. 

Savant Labs are equipped to respond quickly to customer needs for ASTM D6335 TEOST® 33C and ASTM D7097 TEOST MHT® data with experienced chemists and informative reports of the data. Beyond this, as the developer of both methods, Savant Labs has the expertise to modify the conditions of test to emulate advanced engine needs and effects on engine oils. Such customized projects and testing protocols can thus be developed to advance understanding of oxidation resistance of engine oils of the future.  The complete technical brief is available.