Volatility is an important engine oil property, particularly as lower viscosity oils become more popular. There is a direct association with an oil’s volatility characteristics and oil consumption rates. ASTM 5800 is the standard test method for measuring engine oil volatility by the Noack Method. This test method covers three procedures. Procedure A uses the Noack evaporative tester equipment. Procedure B uses the automated non-Woods metal Noack evaporative apparatus. Procedure C uses the Selby-Noack volatility test equipment.
ASTM 5800 is one of the test methods being monitored by the Test Monitoring Center (TMC) based in Pittsburgh, Penn., U.S.A. There are seven participating labs with a total of 21 stands. According to the most recent TMC report, comparing the past 19 months of data on the new reference oils to the prior 19 months on the old reference oils showed a modest decrease in overall severity and “somewhat worse overall precision.”
The report does not specify which procedure was actually trending severe, however it’s been common knowledge within the industry that Procedure B has had poor precision for several years. However, the Surveillance Panel decided not to declare the test out of control. Instead, three task forces have been formed to address the problem, it was heard at the ASTM Subcommittee D02.B on Automotive Lubricants meeting on 24 June 2015 in Fort Lauderdale, Fla., U.S.A.
A task force has been formed to improve the performance of Procedure B and another to improve the performance of Procedure C. A third task force has been formed to propose warning and action limits and develop control charts, which will allow the Surveillance Panel to define in the future when the test is “out of control.”