Oil Breakdown
No matter what the subject, more complicated fails sooner. Why should multiple viscosity oils be any different ?
First off, ALL engine oils are multiple viscosity. Viscosity is based on temperature.
So we need to use correct terminology. We are discussing multi GRADE oils. I'm not going to type an AJ length tome (AJ is the KING of the FABO tome) but you need to do some study and get on the phone.
When discussing multi GRADE oils, the base oil is always the WINTER grade number. You can have a 10w30, 10w40 or even a 10w50 and they are ALL 10 grade oils. They add VISCOSITY INDEX IMPROVERS to make the other side of the grade.
As a general rule (specifically synthetic oil) the base stock NEVER wears out. The additive package gets used up. Engine oils MUST have the additive package or they fail.
That's why some EXPENSIVE oils can go much longer between oil changes. They use a greater additive package.
The flat earth ears and flu stones among us will tell us how their two dollar a quart Walmart oil has powered their car to national event wins, set many national records, and can go a million miles in their Honda.
The fact is, base stock is almost a secondary consideration. All this BS about TBN and all that, is hog wash.if you burn alcohol, or alcohol base fuels then base oil is a bigger factor. Otherwise, group IV base stocks are where you start.
