The other major breakdown is in the alkaline additives. This breakdown is indicated by
the drop that takes place in the total base number of the oil (T.B.N.). As you can see by
the curve, over a period of running time, this T.B.N. number gradually decreases. So, if
we do not change the oil at a reasonable period then we are at risk of corrosive acids
creating undue engine wear. Having covered the major reasons that create the need for
changing our oil, Let's look at main filtration and what determines
the efficiency level.