Oil ? Re: classification SJ SG SF SH etc...
Posted April 28, 2004 - 12:18 PM
My Honda VFR calls for either a SF or SG, yet the honda oil HP4 is a "SJ" oil. How much does this really matter?
Posted April 28, 2004 - 12:26 PM
The American Petroleum Institute (API) Service Classifications are based on two engine service groups and a quality rating. The current API Service Classifications have been in use since 1972. For engines manufactured before 1972 the owner's or operator's manual will designate an oil according to an older API system. Consult an equipment dealer if there is a question about which classification of oil to use.
A typical API Service Classification found on a can or bottle is SG-CE. (See Figure 1.) The first letter of each of these pairs (S and C) denote the engine service group. API recognizes two engine service groups: the S series and the C series. The "S" stands for spark ignition - engines fueled by gasoline, alcohol, natural gas or propane. The "C" stands for compression ignition - oil fueled (diesel) engines.
The second letter of the pair denotes the quality rating. At this time a high quality rating for an oil is designated by the letter F or G. New quality ratings are assigned as better classes of oils are developed and tested. Generally, the new higher quality oils can be used where lower ratings were specified for older engines.
The engine service group and the quality rating are combined to give the API service classification such as SG or CE. The SG means it is for a spark ignition engine and has a quality rating of G. The CE means the oil is for a compression ignition engine and has a quality rating of E. A given oil may satisfy both engine service groups and have an API service classification of SG-CE, for example. Currently, SG (spark ignition, G quality rating) and CE (compression ignition, E quality rating) are the top engine oils in their respective categories.
The Society of Automotive Engineers (SAE) has established a scale which indicates oil thickness (viscosity). SAE numbers include, for example, 10W-30, 5W-40 and sometimes just a single number such as 5W, 10W, 20, 30, 40 or 50. The "W" next to a number means the oil thickness was measured at a very cold temperature, as low as -35 degrees F, when the oil is thickest. A number without a W suffix indicates the oil thickness was measured when the oil was hot (210 degrees F).
Two numbers separated by a hyphen indicate a multiviscosity oil. Multiviscosity oils are tested at both hot and cold temperatures and are recommended for all-season use. Multiviscosity oils are able to lubricate moving parts over a wide range of temperatures. These oils contain a viscosity index improver or polymers to change the viscosity of the oil as temperature changes. A multiviscosity oil such as a 10W-40 will function like an SAE 10W oil at cold temperatures and like an SAE 40 oil when the temperatures are warm or hot. Note that a multiviscosity oil can not be made by combining individual SAE oil viscosities together. Multiviscosity oils require the addition of polymers in order to gain the ability to function differently at different temperatures. Equipment operator's and service manuals specify which oil viscosity should be used under specific weather conditions.
and some more light reading
A. A comparison of SJ vs. SH for commonly used viscosity grades:
Effective October 15, 1996 motor oils can be labeled with the latest API Service Category - SJ. For the time period of October 15, 1996 to August 1, 1997, oils can be labeled SJ OR SH, but not both. After August 1, 1997 only the SJ designation will be allowed.
The major differences between SJ and SH are:
- Reduced phosphorus levels are required to meet SJ criteria. Phosphorus has been considered to potentially degrade the catalysts used in emission control systems.
- Reduced volatility levels are required to meet SJ criteria. Volatility is a measure of the tendency of the liquid oil to evaporate at elevated temperatures. Once oil molecules move into the gas phase they can be pushed out of the engine with fuel exhaust gases, leading to oil consumption and more stress on the emission control systems.
- A new fuel economy test - Sequence VIA (Six A) - has been established. The test compares motor oils against a standard fluid, and establishes the criteria for claiming energy savings vs that standard fluid in modern, low friction engines.
In addition, several lab test requirements were changed for the SJ Service Category, including measures of filterability, foaming tendency, and high temperature deposit formation.
In summary, API SJ represents an improved quality level of motor oil vs API SH. API SJ oils can be used in any applications where SH oils were being appropriately used. So if your owner’s manual calls for an API SE, SF, SG or SH motor oil - API SJ will work just fine.
The API Service Category Classification System:
Engine oils are currently classified by a two letter code. Diesel engine oil categories start with the letter C (originally designated "Commercial" oils, we associate the C with "compression ignition" used in diesel engines) and gasoline categories start with the letter S (originally designated "Service" oils, we associate the S with "spark ignition" used in gasoline engines). The second letter is simply a sequential designation of improving quality levels over time. In other words, when a new industry quality level is established the next letter of the alphabet is used (so SJ replaces SH). The letter "I" was purposefully skipped to eliminate potential confusion with other commonly used designations.
The codes and viscosity grade are shown in an API "donut" on the back label of Mobil motor oil. API also establishes industry guidelines on what can and can't be included in the donut.
The current designation system was implemented in 1971. At that time, quality categories were established for oils that were used from the early 1930's through the current time.
Today, currently active API service categories (SJ and SH) are defined as those supported by performance tests for which:
1. Specified test equipment is still readily available,
2. Test support materials, such as reference engine oils, are still readily available,
3. Monitoring of the test procedure is being performed by the test developer or the ASTM.
The following categories have been declared obsolete:
SA: Adopted in 1971, but known as API Regular prior to then. This performance category identified mineral oils which contained no performance additives and were intended for the service lubrication of certain low-performance gasoline powered automotive engines typical of the period 1900 to 1930 in North America. Because these oils did not contain any detergent additives, they were also commonly called "non-detergent".
SB: Adopted in 1971, but known as API Premium prior to then. This performance category identified engine oils typical of the period 1931 to 1963 in North America. These oils contained some minimum level of performance additives and offered mild anti-scuff capability, some limited resistance to oil oxidation and some copper/lead bearing corrosion protection. These oils were also referred to as "non-detergent".
SC: Adopted in 1971, but known as API MS prior to then. This performance category identified engine oils typical of the period 1964 to 1967 North America. These oils had to meet the performance requirements of a new "Multicylinder Sequence (MS) engine test. The MS tests were selected to evaluate protection against low temperature sludge, deposits, rust, corrosion and wear.
SD: Adopted in 1971, and also known as API MS prior to then. This performance category identified engine oils typical of the period 1968 to 1971 in North America. The engine tests for this classification included testing the cleanliness of the positive crankcase ventilation valves during short trips and stop-and-go driving.
SE: This performance category identified oils suitable for vehicles manufactured in the 1972-1979 period in North America. The MS tests were again upgraded to evaluate high temperature oil thickening.
SF: This performance category identified oils suitable for vehicles manufactured in the 1980-1988 period in North America. Once again the multicylinder tests were upgraded, adding evaluations particularly appropriate for smaller, higher revving, higher operating temperature engines.
SG: This performance category identified oils suitable for vehicles manufactured in the 1989-1992 period in North America. Oils meeting this service category provided improved engine cleanliness and wear protection for both stop-and-go driving and high speed highway service.