For detailed test results visit 2016 5W30 Oil Comparison TEOST 33c Update: In 2016 AMSOIL subjected Royal Purple 5W30, Mobil1 Extended Performance 5W30 and AMSOIL signature series 5W30 to ASTM TEOST 33c test. Objective: Compare the performance in laboratory tests and cost-effectiveness of AMSOIL Signature Series Synthetic Motor Oil to several passenger-car/light-truck synthetic motor oils widely considered by marketers and con- sumers to be the best available. Note: All Tests are Performed by Independent ASTM Lab
