Engine Oil Essentials

What is engine oil?

Finished engine oil is comprised of 70-90% of base oil and 10-30% of additives.

Base Motor Oil Functions:

  • Provide a viscous film to prevent metal to metal contact
  • Remove heat from internal engine parts
  • Circulate the additives

Motor Oil Additive Functions:

  • Pour Point Depressant - low temperature fluidity booster
  • V.I. Improver - high temperature viscosity booster
  • Anti-wear, Extreme Pressure and Friction Modifiers
  • Detergent, Dispersant
  • Anti-rust, corrosion, acid, foam
Oil Base Oil Types
  1. Mineral oils
  2. Unconventional oils
  3. Synthetic oils

Base Motor Oil Properties:

  • Viscosity - Measurement of engine oil's resistance to flow. Measured at 40 Celsius and 100 Celsius and given a weight based on that measurement.
  • Viscosity Index (V.I)  - The physical property  of oil causes it to become thinner at higher temperatures. An oil with high V.I. (less thinning) will display more consistent and stable performance characteristics in the engine at all temperatures.
  • HTHS Viscosity - High temp, High Shear viscosity uses a dynamic shear test at 150 Celsius to replicate working viscosity of the engine oil in the bearings of the engine. European Car manufacturers use this measurement to ensure that oils are viscous enough to provide maximum protection for turbo charged gas and diesel engines.

20 30 40 (0, 6, 10w) 40 (15,20,25w) 49
mPa.S @ 150 Celsius >2.6 >2.9 >2.9 >3.7 >3.7


American Petroleum Industry is the primary standards body for engine oil in North America.

ILSAC (International Lubricant Standardization and Approval Committee) represents the interest of American and Japanese manufacturers to the API.

Both API and ILSAC use an alpha numeric system to superseding approvals.

1994 -1996 SH GF-1
1997 - 2000 SJ GF-2
2001 - 2004 SL GF-3
2005 - Present SM GF-4

The API trademark "starburst" and "donut" communicate the performance level of the oil to the consumers.

The primary weakness if the API system is the inability to position one approved products as an upgrade to another. Car manufacturers produce cars with vastly different performance levels, but the oil standard is exactly the same. This has spawned the widespread use of the word "synthetic" to denote an upgrade product, rather than a quantifiable performance improvement.


The Association of Constructors of European Automobiles, is an auto manufacturers association, and geared to the requirements of the cars more so than the oil companies. This has allowed the manufacturers to, push a long drain regime that reduces oil usage but improves the overall quality of the oil.

Factory fill oils in Europe are now almost exclusively full synthetic products.

BMW Approved TOTAL QUARTZ Lubricants





Drain Interval

Fuel Economy




<15,000 kms

High Performance - Turbo + Extended Drain




>15,000 kms

High Performance + FE + Extended Drain




<30,000 kms

Fuel Economy

Most new cars sold in Europe are diesel or turbocharged, these engines require thick film oils for maximum protection.

Most new cars sold in North America have large displacement, low revving, naturally aspirated engines which deliver significant fuel economy benefits from thin film oils.

The push for fuel economy from ILSAC and API, couples with the lack of HTHS viscosity limits, promotes low viscosity engine oils that compromise long-term durability.  

Related Topics:
FUCHS Synthetic Motor Oil for BMW - Mercedes - Porsche & Other Luxury Cars
What could be done wrong possibly with a simple oil change
TOTAL synthetics motor oils related F. A. Q.
Computerized Engine Analysis
Oil Recommendations by BMW
BMW Approval for TOTAL Motor Oil
European Cars Motor Oil Specifications
The Importance of Oil Changes
AdBlue & Clean Diesel facts



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