Hey guys, is engine protection reduced when using C3 oil versus the current A3/B4. Both specs have a minimum HTHS viscosity of 3.5 and both have the same wear protection. I can get 5w40 synthetic C3 for 30% less than the current A3/B4 so if it would be good to switch for a cheaper oil. What are the benefits of the first oil type versus the other? If they have the same wear protection according to the test, why does A3/B4 exist, except the fact that it allows longer OCI because of higher TBN? Will the lower TBN in the C3 oil provide less engine cleanliness or the same amount of cleanliness but for a shorter duration (TBN gets depleted)? The first oil type is Mid-SAPS and the latter Full-SAPS. I change my oil every 6k miles and do 90% highway miles at relatively low speed (55-60 MPH).