1.1 ,This test method is commonly referred to as the Sequence VH test, and it has been correlated with the Sequence VG test. The Sequence VG test was previously correlated with vehicles used in stop-and-go service prior to 1996, particularly with regard to sludge and varnish formation.3 It is one of the test methods required to evaluate oils intended to satisfy the API SN, SN Plus performance category.