BOI Doesnt Work Well with Group III
Base Oil Interchange and Viscosity Grade Read Across guidelines have worked well for the industry since their adoption. As explained by Chris Castanien Technical Services Manager-Americas for Neste, Well supported BOI and VGRA results reduce testing time and cost and provide blender flexibility. However, they also inject a certain amount of uncertainty into the system, which must be managed.
He added that weakly supported BOI/VGRA can lead to reduced engine performance and emissions control over time if an oil fails to meet design requirements. In addition, control tolerances can be lost as wear abrades surfaces, volatility can increase thermal loading on the oil and deposits can build up, reducing compression and causing wear. Finally, fuel economy can be lost due to oil thickening and deposits.
Working outside tested BOI/VGRA guidelines amounts to improvising without support data, Castanien cautioned. Proper use of BOI guidelines protects the consumer, engine manufacturer, oil marketer and additive supplier, he added.
ATIEL and API provide specific BOI and VGRA guidelines for marketers and blenders. However, while these guidelines work well for API Group I and II base oils, Group III BOI is more complicated because the oils contribute to test performance.
In recent years, almost every major additive company, many major oil marketers and base oil manufacturers have repeated this message at industry meetings, said Castanien. These presentations have included test data showing the significant performance effect of different Group III base oils on specific tests.
Castanien explained that the problem is only getting worse because Group III differences are expanding as the universe of Group III base stocks continues to grow with new technologies and treatments. Even similar manufacturing trains yield different molecules, depending on crude oil selection and operating conditions.
Unfortunately, traditional bench test methods such as saturates and sulfur standards are not good predictors of engine performance for these molecules, said Castanien. Further test development and correlation work are needed, he added.
Currently, BOI is agreed on a test-by-test basis, using specific slates of base oils having different physical and chemical properties. All the newly introduced and upgraded specifications will add at least 17 new tests, many of them lengthy and expensive.
The industry has never before faced the near simultaneous introduction of so many tests. Funding, running and analyzing so many tests for BOI will be very challenging, Castanien concluded.