Basic Engine Oil Knowledge

Engine oil: engine's lifeblood

Complex task in many different environments?


  • Lubrication
  • Cool
  • Protects against
    • wear
    • combustion acids
    • rust
  • Clean
  • Keeps contaminants / soot in oil
  • Hydraulic fluid for injectors etc.

Engines and engine oil

The engine is composed of following parts through which the engine oil flows.


  • If engine is a heart, the engine oil is its blood.
  • Oil circulates in the engine and performs various functions.

Functions of engine oil


  • Engine oil is necessary to maintain engine and enable it to function

How gasoline engine works

  • Gasoline engine produces power by repeat combustion of air-fuel mixture.
  • The air-fuel mixture is ignited by a spark at the spark plug.

Why new generation engine oils?

Significant changes in engines: stresses oil


  • engine power
  • oil drain intervals
  • sump temperatures


  • sump size
  • lower oil consumption

And finally biggest factor....

  • engine designs to meet low emission standards

Causes of engine failures

  • Improper maintenance
  • Incorrect oil used
  • Failure to change contaminated oils
  • Sludge deposits
  • Build-up of varnish
  • Oxidation & thickening of oil
  • Abrasive elements
  • Additive depletion
  • Oil pump failure

Why engine oil must be changed?

Engine oil deteriorates for the following reasons:

  • Dirt accumulation
  • Moisture contamination
  • Fuel Contamination
  • Thermal oxidation of the oil
  • Consumption of additives


  • Temperature of combustion gases in engine reaches 2000 to 3000℃.
  • In such a severe environment, it is evident that engine oil will deteriorate

Symptoms of engine oil deterioration

  • Dirt builds up in engine
  • Engine is not protected
  • Reduced fuel economy
  • Reduced performance
  • Reduced engine life
  • Engine breakdown


  • The deterioration of engine oil causes engine trouble.
  • Engine Oil must be changed periodically to keep engine in best condition

Points to choose engine oil

The quality and viscosity of the engine oil are specified by international standards. By noting these, the appropriate engine oil can be chosen.

SAE viscosity notation

Sample SAE viscosity notation

SAE 10W-40

Grade notations (API, ILSAC, ACEA)

Sample grade notations


Sample certification marks

How to read SAE viscosity notation

The viscosity of the engine oil is expressed numerically using the SAE (Society of Automotive Engineers) developed notation.

  • “W” stands for “Winter”.

Basics of transmission

What is a Transmission?

The transmission transmits power from the engine and changes the rotation direction as well as increasing or decreasing engine torque and engine speed. It consists of a large number of rotating and sliding parts for which lubricant is used.

Auto transmission
Continuously Variable Transmissions

Basics of ATF and CVTF

Transmissions and Lubricants

There are mainly 3 different types of transmissions: Automatic Transmissions (AT), Continuously Variable Transmissions (CVT) and Manual Transmissions (MT).
Each type has its own lubricant performance requirements.

Required Performance for ATF and CVTF

The following are the performance requirements for ATF and CVTF.

ATF performance

  • Lubrication properties
  • Viscosity / temperature characteristics
  • Cooling characteristics
  • Materials compatibility
  • Wet clutch friction characteristics

CVT performance

ATF performance
Metal to metal friction characteristics


  • ATF and CVTF must be used correctly as they each meet different performance requirements.

Why ATF and CVTF must be changed?

Deterioration of ATF and CVTF

The following are causes of ATF and CVTF deterioration:

  • Oxidation caused by the heat from driving
  • Consumption and breakdown of additives
  • Accumulation of moisture, metal wear particles and sludge

Symptoms Caused by Deterioration

The following symptoms will occur if the ATF or CVTF deteriorates.

  • Reduced acceleration
  • Reduced fuel efficiency
  • Increased shift shock


  • ATF and CVTF need regular replacement to keep them in the best condition.