HE HISTORY OF LUBRICATION can be traced back as far as
the very beginning of transportation. Until the 19th
century, lubricants were primarily composed of animal
fats and vegetable oils, but a new means of lubrication
and a whole new industry were born when the first crew
successfully drilled for oil in 1859.
Early on, viscosity was identified as one of the most
important characteristics of a motor oil, and oils were
divided into light, medium and heavy viscosity classes.
As soon as instruments capable of measuring viscosity
were introduced, the Society of Automotive Engineers
(SAE) developed a complete viscosity classification
system, which included 11 different viscosity grades.
Viscosity modifiers allowed manufacturers to begin
developing multi-grade oils in 1945.
Engine technology has improved dramatically over
the years, increasing the protection and performance
required of motor oils. In order to meet public demand
for vehicles with greater fuel economy during the oil
embargo of the 1970s, automobile manufacturers produced
smaller, lighter cars powered by smaller and
more efficient engines. When fuel injection became
common on gasoline-fueled engines, it placed even
greater demand on the vehicle’s engine oil as it was
required to flow and reach critical components as
quickly as possible.
In today’s world, high fuel prices and environmental
concerns have driven up demand for high-performance,
fuel efficient, environmentally-friendly vehicles. To meet
this demand, vehicle manufacturers have produced
more aerodynamic cars with reduced air flow through
the engine. Although these vehicles are more fuel efficient,
they exhibit higher engine operating temperatures
than earlier automobiles, putting even greater stresses
on the engine oil in the areas of oxidation stability,
deposit prevention and wear protection.
Established in 1970, the API Engine Service
Classification System (ESCS) was designed to classify
oils according to their performance characteristics and
type of service. In 1993, the API Engine Oil Licensing
and Certification System (EOLCS) was launched, a
voluntary program which allows marketers who meet
the minimum performance requirements to mark their
oil containers with the API certification marks.
API service categories for gasoline engines are comprised
of two letters. The first letter is “S” for “service,”
and the second letter is assigned alphabetically according
to order of development. Thus, the first service
category of “SA” is the earliest, while the latest is “SM.”
Because each new service category exceeds the performance
requirements of the previous category, oils
meeting the current API specification are suitable for
use in all vehicles calling for an older specification.
The introduction of AMSOIL synthetic motor oil in
1972 set all-new standards for motor oil quality and
performance, becoming the first 100 percent synthetic based
motor oil to pass American Petroleum Institute
(API) service requirements. AMSOIL continues to lead
the way in the synthetic market, offering motorists the
ultimate in wear protection, all-temperature performance,
maximum fuel efficiency and extended drain
intervals.
|
API Engine Oil Service Category Chart for Gasoline Engines |
| Category |
Status |
Service |
| SM |
Current |
For all automotive engines currently in use.
Introduced in 2004, SM oils are designed to provide improved oxidation resistance,
improved deposit protection, better wear protection, and better low-temperature
performance over the life of the oil. Some SM oils may also meet the latest ILSAC
specification and/or qualify as Energy Conserving. |
| 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 |
For 1993 and older engines. |
| SF |
Obsolete |
For 1988 and older engines. |
| 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. |
|
Source: www.api.org |