Oil is composed of two things.... Base oil and its Additives
Base oil = this is where your Mineral or Synthetic issue comes in.... base oil alone will not protect your engine.
Additives = this is where many people are not aware of.... Additives determines oil performance....
Here are some that are mixed with your oil at the factory....
Detergent additives, are used to clean and neutralize oil impurities which would normally cause deposits (or sludge) on vital engine parts.
Friction modifiers, like molybdenum sulfide, are used for increasing fuel economy by reducing friction between moving parts.
Viscosity modifiers make an oil's viscosity higher at elevated temperatures. This combats the tendency of the oil to become thin at high temperature.
Deposit control additives prevent the formation of soft sludge and hard deposits of impurities.
Corrosion or rust and oxidation (R&O) inhibiting additives retard the oxidation of metal inside an engine.
Antioxidant additives retard the decomposition of the stock oil.
Antiwear additives or wear inhibiting additives cause a film to surround metal parts, helping to keep them separated.
Pour point depressants improve the oil's ability to flow at lower temperatures.
Anti-foam agents inhibit the production of air bubbles and foam in the oil which can cause a loss of lubrication, pitting, and corrosion where entrained air contacts metal surfaces.
Seal conditioners cause gaskets and seals to swell so that the oil cannot leak by.
Metal deactivators create a film on metal surfaces to prevent the metal from causing the oil to be oxidized.
Extreme pressure agents bond to metal surfaces, keeping them from touching even at high pressure.
Dispersants keep contaminants (e.g. soot) suspended in the oil to prevent them from coagulating.
Wax crystal modifiers are dewaxing aids that improve the ability of oil filters to separate wax from oil. This type of additive has applications in the refining and transport of oil, but not for lubricant formulation.
So, depending on its application... say, for diesel engines, gasoline engines, motorcycle engines, etc., and emission standards, manufacturers have a specific formulation for each type and then assigned those letters on the label... Diesel oils will have more detergent additives than other oils, other oils may have more seal conditioners than others, etc. etc....
