The most important function of lubricants is the reduction of friction and wear and the relative movement of two bearing surfaces is only possible if a  lubricant is present. A Lubricant is either an oil or a grease or a solid used to reduce friction between to surfaces. Lubricants can be classified into two groups: automotive and industrial lubricants – lube oils and greases.

Engine oil viscosity classification SAE J300

The requirements of viscosity classification are determined now by SAE J300 revised in January 2015 by the Society of Automotive Engineers Inc. New York. As the vehicles of European manufacturers have a wide spread occurrence, the basic classification system is ACEA which replaced CCMC classification in 1996 . The development of lubricants is closely linked to the specific applications and application methods, the following section will consider both lubricants and their application.


The viscosity of an engine oil is an indicator of how readily a loadcarrying film can be formed at all lubrication points in an engine. As viscosity is a function of temperature, it applies to all potential ambient and operating temperatures. The first number (15W) refers to the viscosity grade at low temperatures (W from winter), whereas the second number (40) refers to the viscosity grade at high temperatures.

SAE -grade Cold Cranking
(CCS)
Cold Pumping
(MRV)
Kinematic Viscosity,
100°C
HTHS, 150 °C
(cP @ T °C) (cP @ T °C) (cSt) (cSt) (cP)
Maximum Maximum Minimum Maximum Maximum
0W 6,200 @ -35 60,000 @ -40 3.80    
5W 6,600 @ -30 60,000 @ -35 3.80    
10W 7,000 @ -20 60,000 @ -30 4.10    
15W 7,000 @ -15 60,000 @ -25 5.60    
20W 9,500 @ -15 60,000 @ -20 5.60    
25W 13,000 @ -10 60,000 @ -15 9.30    
8     4.00 < 6.1 1.70
12     5.00 < 7.1 2.00
16     6.10 < 8.2 2.30
20     6.90 < 9.3 2.60
30     9.30 < 12.5 2.90
40     12.50 < 16.3 3.50
(0W-40, 5W-40, 10W-40)
40     12.50 < 16.3 3.70
(15W-40, 20W-40, 25W-40,40)
50     16.30 < 21.9 3.70
60     21.90 < 26.1 3.70
1 mPa·s = 1cP; 1mm²/s =1 cSt

 

Type of Synthetic Base oil Compatibility with Mineral Oils
Polyalphaolefins (PAO) excellent
Polyglycols (PAG) bad
Esters (E ) good
Phosphate esters (PH) bad
Siliconoils (SI) bad

 

ACEA European Oil sequences-guideline

Three main factors specifically affecting the european market:

  • Extended oil drain intervals
  • Fuel savings
  • Exhaust gas composition

 

ACEA specifications are guidelines for European cars. The different uses of the oils are labelled by the European ACEA 2012 classification by letter:

A / B - for passenger car gasoline and light duty diesel engines
C - for passenger cars gasoline and light duty diesel engines with after treatment devices
E - for commercial vehicles with heavy duty diesel engines

ACEA A / B for gasoline and diesel engine oils

A1 / B1 Stable, stay-in-grade oil intended for use at extended drain intervals in gasoline engines and car & light van diesel engines specifically designed to be capable of using low friction low viscosity oils with a high temperature / high shear rate viscosit+y of 2.6 mPa*s for xW / 20 and 2.9 to 3.5 mPa*s for all other viscosity grades. These oils are unsuitable for use in some engines. Consult owner manual or handbook if in doubt.
A3 / B3 Stable, stay-in-grade oil intended for use in high performance gasoline engines and car & light van diesel engines and / or for extended drain intervals where specified by the engine manufacturer, and / or for year-round use of low viscosity oils, and / or for severe operating conditions as defined by the engine manufacturer.
A3 / B4 Stable, stay-in-grade oil intended for use in high performance gasoline and direct injection diesel engines, but also suitable for applications described under A3 / B3.
A5 / B5 Stable, stay-in-grade oil intended for use at extended drain intervals in high performance gasoline engines and car & light van diesel engines designed to be capable of using low friction low viscosity oils with a High temperature / High shear rate (HTHS) viscosity of 2.9 to 3.5 mPa*s. These oils are unsuitable for use in some engines. Consult owner manual or handbook if in doubt.

 

ACEA C for Catalyst compatibility oils

C1 Stable, stay-in-grade oil intended for use as catalyst compatible oil in vehicles with DPF and TWC in high performance car and light van diesel and gasoline engines requiring low friction, low viscosity, low SAPS oils with a minimum HTHS viscosity of 2.9 mPa*s. These oils will increase the DPF and TWC life and maintain the vehicles fuel economy. Warning: these oils have the lowest SAPS limits and are unsuitable for use in some engines. Consult owner manual or handbook if in doubt.
C2 Stable, stay-in-grade oil intended for use as catalyst compatible oil in vehicles with DPF and TWC in high performance car and light van diesel and gasoline engines designed to be capable of using low friction, low viscosity oils with a minimum HTHS viscosity of 2.9 mPa*s. These oils will increase the DPF and TWC life and maintain the vehicles fuel economy. Warning: these oils are unsuitable for use in some engines. Consult owner manual or handbook if in doubt.
C3 Stable, stay-in-grade oil intended for use as catalyst compatible oil in vehicles with DPF and TWC in high performance car and light van diesel and gasoline engines, with a minimum HTHS viscosity of 3.5 mPa*s. These oils will increase the DPF and TWC life. Warning: these oils are unsuitable for use in some engines. Consult owner manual or handbook if in doubt.
C4 Stable, stay-in-grade oil intended for use as catalyst compatible oil in vehicles with DPF and TWC in high performance car and light van diesel and gasoline engines requiring low SAPS oil with a minimum HTHS viscosity of 3.5 mPa*s. These oils will increase the DPF and TWC life. Warning: these oils are unsuitable for use in some engines. Consult owner manual or handbook if in doubt.
SAPS : Sulphated Ash, Phosphorus, Sulphur
DPF : Diesel Particulate Filter
TWC : Three way catalyst
HTHS : High temperature / High shear rate viscosity

 

 

ACEA E for Heavy Duty Diesel engine oils

E4 Stable, stay-in-grade oil providing excellent control of piston cleanliness, wear, soot handling and lubricant stability. It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV and Euro V emission requirements and running under very severe conditions, e.g. significantly extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for engines without particulate filters, and for some EGR engines and some engines fitted with SCR NOx reduction systems. However, recommendations may differ between engine manufacturers so Driver Manuals and / or Dealers shall be consulted if in doubt.
E6 Stable, stay-in-grade oil providing excellent control of piston cleanliness, wear, soot handling and lubricant stability.It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV and Euro V emission requirements and running under very severe conditions, e.g. significantly extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for EGR engines, with or without particulate filters, and for engines fitted with SCR NOx reduction systems. E6 quality is strongly recommended for engines fitted with particulate filters and is designed for use in combination with low sulphur diesel fuel. However, recommendations may differ between engine manufacturers so Driver Manuals and / or Dealers shall be consulted if in doubt.
E7 Stable, stay-in-grade oil providing effective control with respect to piston cleanliness and bore polishing. It further provides excellent wear control, soot handling and lubricant stability. It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV and Euro V emission requirements and running under severe conditions, e.g. extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for engines without particulate filters, and for most EGR engines and most engines fitted with SCR NOx reduction systems. However, recommendations may differ between engine manufacturers so Driver Manuals and / or Dealers shall be consulted if in doubt.
E9 Stable, stay-in-grade oil providing effective control with respect to piston cleanliness and bore polishing. It further provides excellent wear control, soot handling and lubricant stability. It is recommended for highly rated diesel engines meeting Euro I, Euro II, Euro III, Euro IV and Euro V emission requirements and running under severe conditions, e.g. extended oil drain intervals according to the manufacturer’s recommendations. It is suitable for engines with or without particulate filters, and for most EGR engines and for most engines fitted with SCR NOx reduction systems. E9 is strongly recommended for engines fitted with particulate filters and is designed for use in combination with low sulphur diesel fuel. However, recommendations may differ between engine manufacturers so Drivers Manuals and / or Dealers should be consulted if in doubt.

 

API Classification have been made by AMERICAN PETROLEUM INSTITUTE API, ENGINE OIL LICENSING AND CERTIFICATION SYSTEM EOLCS.

Engine Oil Guide

1. Performance Level
Motor oils designed for cars, vans, and light trucks with gasoline engines fall under API’s “S” (Service) categories. Motor oils designed for heavy duty trucks and vehicles with diesel engines fall under API’s “C”(Commercial) categories. Please see the Gasoline Engines and Diesel Engines charts for descriptions of current and obsolete API service categories.

2. Viscosity Grade:
Measure of oil’s thickness and ability to flow at certain temperatures. Vehicle requirements may vary. Follow your vehicle manufacturer’s recommendations on SAE oil viscosity grade.

3. Resource Conserving and Energy Conserving:
These designations apply to oils intended for gasoline-engine cars, vans, and light trucks. Widespread use of “Resource Conserving” or “Energy Conserving” oils may result in an overall savings of fuel in the vehicle fleet as a whole.

4. Multiple Performance Levels:
Oils designed for diesel engine service might also meet gasoline engine service. For these oils the designation is “C” category first followed by the “S” category. “C” category oils have been formulated primarily for diesel engines and may not provide all of the performance requirements consistent with vehicle manufacturers’ recommendations for gasoline fueled engines.

 

Guide to SAE VISCOSITY GRADES OF ENGINE OIL for PASSENGER CARS

Multigrade oils such as SAE 5W-30 and 10W-30 are widely used because, under all but extremely hot or cold conditions, they are thin enough to flow at low temperatures and thick enough to perform satisfactorily at high temperatures. Note that vehicle requirements may vary.

Follow your vehicle manufacturer’s recommendations on SAE oil viscosity grade.

If lowest expected outdoor temperature is: Typical SAE Viscosity Grades for Passenger Cars:
0°C (32°F) 0W-20
0W-30
5W-20
5W-30
10W-30
10W-40
20W-50
–18°C (0°F) 0W-20
0W-30
5W-20
5W-30
10W-30
10W-40
Under –18°C (0°F) 0W-20
0W-30
5W-20
5W-30

 

The current and previous API Service Categories are listed below. Vehicle owners should refer to their owner’s manuals before consulting these charts. Oils may have more than one performance level.

For automotive gasoline engines, the latest engine oil service category includes the performance properties of each earlier category. If an automotive owner’s manual calls for an API SJ or SL oil, an API SM oil will provide full protection. For diesel engines, the latest category usually – but not always – includes the performance properties of an earlier category.

 

GASOLINE ENGINES

SN Current
Introduced in October 2010, designed to provide improved high temperature deposit protection for pistons, more stringent sludge control, and seal compatibility. API SN with Resource Conserving matches ILSAC GF-5 by combining API SN performance with improved fuel economy, turbocharger protection, emission control system compatibility, and protection of engines operating on ethanol-containing fuels up to E85.
SM Current
For 2010 and older automotive engines.
SL Current
For 2004 and older automotive engines.
SJ Current
For 2001 and older automotive engines.
SH Obsolete
For 1996 and older engines.
SG Obsolete
CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1993. May not provide adequate protection against build-up of engine sludge, oxidation or wear.
SF Obsolete
CAUTION: Not suitable for use in most gasoline-powered automotive engines built after 1988. May not provide adequate protection against build-up of engine sludge
SE Obsolete
CAUTION: Not suitable for use in gasoline-powered automotive engines built after 1979.
SD Obsolete
CAUTION: Not suitable for use in gasoline-powered automotive engines built after 1971. Use in more modern engines may cause unsatisfactory performance or equipment harm.
SC Obsolete
CAUTION: Not suitable for use in gasoline-powered automotive engines built after 1967. Use in more modern engines may cause unsatisfactory performance or equipment harm.
SB Obsolete
CAUTION: Not suitable for use in gasoline-powered automotive engines built after 1951. Use in more modern engines may cause unsatisfactory performance or equipment harm.
SA Obsolete
CAUTION: Contains no additives. Not suitable for use in gasoline-powered automotive engines built after 1930. Use in more modern engines may cause unsatisfactory performance or equipment harm.

 

API C DIESEL ENGINES

CJ-4 Current
For high-speed four-stroke cycle diesel engines designed to meet 2010 model year on-highway and Tier 4 nonroad exhaust emission standards as well as for previous model year diesel engines. These oils are formulated for use in all applications with diesel fuels ranging in sulfur content up to 500 ppm (0.05% by weight). However, the use of these oils with greater than 15 ppm (0.0015% by weight) sulfur fuel may impact exhaust aftertreatment system durability and / or drain interval. CJ-4 oils are especially effective at sustaining emission control system durability where particulate filters and other advanced aftertreatment systems are used. Optimum protection is provided for control of catalyst poisoning, particulate filter blocking, engine wear, piston deposits, low- and high-temperature stability, soot handling properties,oxidative thickening, foaming, and viscosity loss due to shear. API CJ-4 oils exceed the performance criteria of API CI-4 with CI-4 PLUS, CI-4, CH-4, CG-4 and CF-4 and can effectively lubricate engines calling for those API Service Categories.When using CJ-4 oil with higher than 15 ppm sulfur fuel, consult the engine manufacturer for service interval.
CI-4 Current
Introduced in 2002. For high-speed, four-stroke engines designed to meet 2004 exhaust emission standards implemented in 2002. CI-4 oils are formulated to sustain engine durability where exhaust gas recirculation (EGR) is used and are intended for use with diesel fuels ranging in sulfur content up to 0.5% weight. Can be used in place of CD, CE, CF-4, CG-4, and CH-4 oils. Some CI-4 oils may also qualify for the CI-4 PLUS designation.
CH-4 Current
Introduced in 1998. For high-speed, four-stroke engines designed to meet 1998 exhaust emission standards. CH-4 oils are specifically compounded for use with diesel fuels ranging in sulfur content up to 0.5% weight. Can be used in place of CD, CE, CF-4, and CG-4 oils.
CG-4 Obsolete
Introduced in 1995. For severe duty, high-speed, four-stroke engines using fuel with less than 0.5% weight sulfur. CG-4 oils are required for engines meeting 1994 emission standards. Can be used in place of CD, CE, and CF-4 oils.
CF-4 Obsolete
Introduced in 1990. For high-speed, four-stroke, naturally aspirated and turbocharged engines. Can be used in place of CD and CE oils.
CF-2 Current
Introduced in 1994. For severe duty, two-stroke-cycle engines. Can be used in place of CD-II oils.
CF Current Introduced in 1994. For off-road, indirect-injected and other diesel engines including those using fuel with over 0.5% weight sulfur. Can be used in place of CD oils.
CE Obsolete
CAUTION: Not suitable for use in most diesel-powered automotive engines built after 1994.
CD-II Obsolete
CAUTION: Not suitable for use in most diesel-powered automotive engines built after 1994.
CD Obsolete
CAUTION: Not suitable for use in most diesel-powered automotive engines built after 1994.
CC Obsolete
CAUTION: Not suitable for use in diesel-powered engines built after 1990.
CB Obsolete
CAUTION: Not suitable for use in diesel-powered engines built after 1961.
CA Obsolete
CAUTION: Not suitable for use in diesel-powered engines built after 1959.

 

API EC Energy Conserving

EC 1 min. 1.5% fuel savings compared to a SAE 20W-30 reference oil in a 82’er Buick-petrol engine VG, 3.8 L.,SEQ VI-Test
EC II as API EC 1, but min. 2.7% fuel savings
EC replaces API EC 1 & II. Only in conjunction with API SJ. Fuel savings: OW-20, 5W-20> 1.4%, OW-XX, 5W-XX> 1.1%, 10W-XX, other > 0.5%, SEQ VI A-Test: 93’er Ford V8, 4.6 L., reference oil 5W-30.

 

The ILSAC (International Standardization and Approval Commitee) uses together with another American Institute and the JAMA (Japan Automobile Manufacturers Association) the API Classifikationen for an individual ILSAC Standard:

GF-5 Current
Introduced in October 2010, designed to provide improved high temperature deposit protection for pistons and turbochargers, more stringent sludge control, improved fuel economy, enhanced emission control system compatibility, seal compatibility, and protection of engines operating on ethanol-containing fuels up to E85.
GF-4 Obsolete
Use GF-5 where GF-4 is recommended.
GF-3 Obsolete
Use GF-5 where GF-3 is recommended.
GF-2 Obsolete
Use GF-5 where GF-2 is recommended.
GF-1 Obsolete
Use GF-5 where GF-1 is recommended.

 

MIL-Spezifications (Military Standard in USA):

MIL-L Lubcricants
MIL-G Greases, Hydraulic fluids