http://www.amsoil.com/performancetests/sequence_3f.htm Even at three times the standard test length, AMSOIL 10W-30 performed three times better than the test limit in the area of kinematic viscosity increase, and it excelled in all areas of the test. AMSOIL 10W-30 Motor Oil kept viscosity increase, wear, deposits and varnish to a minimum. While conventional motor oils tend to thicken and lose their lubricating effectiveness, AMSOIL Motor Oils are formulated to maintain their viscosities over extended drain intervals. The results of the Sequence IIIF test clearly demonstrate the long drain capability of AMSOIL 10W-30 Motor Oil. Even after being subjected to a triple length Sequence IIIF test, AMSOIL 10W-30 performed three times better than the standard test limits. The competitor's motor oil shows dramatic viscosity increase in less than half the time.