5.1 API SPECIFICATIONS
These define three categories of lubricants identified by a two-letter
code. The first distinguishes the engine for which it is intended:
S means Service (petrol vehicles), C means Commercial (diesel vehicles),
G for transmissions.
The second letter indicates the performance level: the further down
the letter is in the alphabet, the higher the performance level.
The latest specification for petrol vehicles is API SL while for
diesel vehicles recently API specifications API CH-4 and CI-4 have
The tests required by the API, from SH onwards, are carried out
following the rules of the CMA protocol (engine test control, formulation
control, data control).
To obtain this classification, a lubricant must pass four engine
tests, which consider:
- the increase of the engine oil temperature in service
- the lengthening of the interval between oil changes established
by the manufacturers
- engine performance research
- strictness of environment protection standards
- reduction of fuel consumption due to low viscosity (only for
"Energy conserving" oils)
API "S" SPECIFICATIONS, for petrol engines
|| For petrol engines of cars and light commercial vehicles
starting from 1989. SG oils have better features than SF in
terms of resistance to the formation of deposits, protection
against wear and resistance to corrosion.
||Same features as SG but more stringent test conditions.
|| Engine oil of SH level, but developed in accordance with
APY certification systems following multiple test criteria.
||Born on July 2001, intruduces limits in terms of stability
to oxidisation, deposit control at high temperatures, reduction
of volatility and consumption rates.
|| Valid from November 2004, it asks for tougher tests about
stability to oxidation, deposit control, performances at low
With regard to OMVs, most Selenia lubricants have passed this specification:
||SELENIA K, SELENIA StAR
||20K, 20K AR, PERFORMER, PERFORMER MULTIPOWER,
API "C" SPECIFICATIONS, for diesel engines
||For diesel engines with indirect injection and for other diesel
engines which use a broad range of lubricants, including those
with a high sulphur content (over 0.5 wt.). Control on deposits
on the pistons, wear and corrosion of the bearings is important
for these engines, which may be naturally aspirated, turbo-charged
and high performance turbo-charged. The oils for these functions
began to exist in 1994 and can be used when specification CD
||Two-stroke diesel heavy-duty engines. Typical for two-stroke
diesel engines, which require effective control on the cylinders,
rings and deposits. The oils designated for this type of service
began to exist in 1994 and can be used also when specification
CD-II is recommended. They do not necessarily meet the requirements
of specification CF or CF-4 even if they do have to pass these
tests as well.
||Diesel engines 1990. Typical high speed service, 4-stroke
engines. It exceeds the requirements of specification CE, providing
more control on oil consumption and deposits on pistons. These
oils ought to be used instead of the oils in category CE. Ideal
for long journeys and harsh conditions of use. When combined
with the appropriate S category, they can also be used for petrol
engines and light diesels (cars, light vehicles, vans) if recommended
by the manufacturer.
||Diesel engines in harsh operating conditions 1994. This specification
describes oils for use in high-speed diesel engines both with
applications under harsh motorway conditions (fuel with 0.05%
of sulphur) and off the motorway (less than 0.5% sulphur in
the fuel). They provide high control on deposit on the pistons
at high temperatures, wear, corrosion, stability to oxidisation,
accumulation of soot and foams. Specific oils for engines built
to meet the used oils emission standards of 1994 and for engines
that require API CD, CE and C-4. These oils began to exist in
||Diesel engines in harsh operating conditions 1998. Ideal oils
for high speeds, 4-stroke engines, which meet the 1998 used
oil emission standards and designed to use diesel fuels with
sulphur content of up to 0.5%. These oils have higher performance
than those that meet API CF-4 and API CG-4.
||Diesel engines in harsh operating conditions 2002. Oils for
use at high speed, 4-stroke diesel engines designed to meet
the 2004 used oil emission standards to be implemented in October
2002. To be used with fuels with sulphur content up to 0.05%.
These oils are effective in supporting engine life when EGRs
are used with other emission-related components. It offers excellent
protection against wear, stability at high and low temperatures,
protection against soot, piston deposit and foam control, loss
of viscosity. These oils have higher performance than API CH-4,
CG-4 and CF-4 oils and can be used in engines for which these
API categories are foreseen.