Total Base Number (TBN) is the measurement
of a lubricants reserve alkalinity. The
higher a motor oils TBN, the more effective
it is in handling contaminants and reducing
the corrosive effects of acids for an extended
period of time. As shown in the graph, AMSOIL
5W-30 Synthetic Motor Oil has a higher TBN than
Mobil 1 SuperSyn 5W-30 Motor Oil.