Additive
packages are added to motor oil and play a key role in helping to keep
an engine clean and protected from varnish and sludge, as well as wear
from heat and acids. Additives can consist of anti-wear agents,
friction modifiers, dispersants, detergents, viscosity index improvers
and antioxidants. Some key cleaning ingredients that make up motor oil
additive packages are detailed below:

• Anti-wear
  additives lay down a protective, sacrificial film between moving parts
  and also help stop oxidation of the motor oil.

• Dispersants grab dirt and sludge before they can build up
  during engine operation, holding them in suspension and preventing them
  from depositing on to engine parts.
• Detergents help keep high-temperature surfaces such as pistons clean.
  Changing the motor oil at proper intervals will help to prevent ring
  sticking and piston deposits.
• Viscosity index improvers are chemical additives that are added to
  motor oil to ensure proper oil viscosity at extreme cold and hot
  operating conditions, enabling the development of multi-grade oils such
  as SAE 5W-20.
• Friction modifiers help to reduce friction in critical areas of the engine, thus enhancing the vehicle’s fuel economy.
• Anti-oxidants stop oil oxidation to help keep the oil from becoming too thick.

Properly functioning engine oils help enhance fuel economy, prevent
sludge and varnish deposits and maintain proper low-temperature
pumpability. The additives in engine oils are consumed during use at
different rates, which vary with vehicle, engine type and driving
conditions; therefore, it is not possible to establish a universal oil
drain interval. Always follow the recommended oil drain interval and
oil specifications found in the owner’s manual.

Tech Tip courtesy of Pennzoil, www.pennzoil.com.