Engine oil volatility is commanding considerable attention as engine oil viscosity creeps lower and drain intervals extend further. Accordingly, considerable effort is being made to improve the precision and consistency of instruments used to measure volatility, and the flaws in ASTM D5800 are becoming glaring.
In September, the ASTM Test Monitoring Center issued a bulletin on the D5800 bench test procedure identifying a monthly severity adjustment for test equipment. TMCs Frank Farber described it as an adjustment to be applied based on an instruments demonstrated severity level using approved Lubricant Test Monitoring System criteria, similar to the way engine tests are adjusted for lab severity bias. The level of adjustment is based on the specific stands reference data, varying from instrument to instrument. This is unprecedented, as ASTM repeatability and reproducibility data are normally the only requirement for bench tests.