Detergent oil and not detergent oil?

All modern motor oils are "detergent" oils - with the possible exception of some short term "running in" oils. The level and type of detergents used vary from oil to oil e.g. :


PCEO (Passenger Car Engine Oils) - low to moderate detergency. These vehicles typically are "light duty" and run on low sulphur (sweet) fuels. Total Base Number (TBN) 5 - 10


CVEO (Commercial Vehicle Engine Oil) - moderate detergency. Usually run on sweet diesel fuel, but capable of accomodating higher sulphur level fuels. TBN 7 - 15


Marine Diesel Engine Oils - Moderate to High detergency - made to accomodate high sulphur bunker fuels. TBN 20 - 150 High calcium load detergent is used to neutralise sulphurous acids formed during the fuel burn.


If you follow a time line for engine oils from about the 1930's forward you find a general improvement in oil performance (higher Viscosity Index, better cold flow properties, better detergent/dispersant packages, and an optimisation of TBN and EP agents). These improvements are characterised by the SAE designation SA ... SM for "service" (petrol) vehicles, CC..CJ-4 for "commercial" (diesel) vehicles.


Non-detergent oils (presumably "straight" non-additivated oils) are rare - apart from medical grade white oil and very low duty, non-EP, turbine, transformer and hydraulic oils. Even most low-duty oils have some type of additive package - antioxidant, mild EP or DDI.