API Engine Service

API Engine Service Categories— gasoline and diesel engine oil quality levels established jointly by API, SAE, and ASTM, and sometimes called SAE or API/SAE categories formerly called API Engine Service Classifications. API Service Categories are as follows ... 

Series 3—obsolete specification for heavy-duty engine oils used in Caterpillar Tractor Company diesel engines. Caterpillar now specifies that the oil for its engines comply with Military Specification MIL-L-2104C or API Engine Service Category CD. 

The API classification system is open ended, so that additional classifications can be added when needed. There is a relationship between API engine service classifications and MIL, OEM and ACEA classifications of the oil quality standards previously outlined. These relationships are shown in Table 2,... 

API Specification for Internal-Combustion Reciprocating Engines for Oil-Field Service, API STD 7B-11C, Eighth Edition, March 1981. 

In the API system the least demanding classification for a petrol engine was originally designated SA. The most demanding is, at present, SG. (The S stands for Service... 

Station.) Constant development of both engines and oils means that from time to time the highest ratings are superseded by even higher ratings. The API system also classifies diesel engine oils by their severity of service. Here the categories have the prefix C, which stands for Commercial. 

Various authorities and military bodies issue specifications relating to the service performance of engine oils. In some instances the ratings are almost identical with those of the API, but most of them are not precisely parallel because they cover performance factors encountered in particular engines and particular categories of service. 

Where liquefied petroleum gas (LPG) engines are used in trucks or buses, oils for API Service SJ are often used for convenience, although somewhat lower quality oils may be satisfactory. In some cases, special oils containing no organometallic detergents (ashless additives) are recommended. 

Japanese vehicle manufacturers. In general, they have relied on the API classification system to recommend engine oils for service-fill applications. There is a parallel with Europe (CEC) in the Japanese Automobile Standards Organization JASO they have developed four engine test procedures without giving pass/fail limits. The parallel is not complete because neither within nor outside Japan do the vehicle manufacturers require any of these tests to be run to meet their own specifications. 

IR monitoring of oxidation process. Monitoring lubricants by infrared spectroscopy is a well established technique. The infrared spectra of oxidized (used) engine oil samples can be split into three parts (a) above 1900 cm 1, (b) 1900 to 1500 cm 1, and (c) below 1500 cm"1. The spectral changes in the region between 1900 to 1500 cm 1 in commercial automotive oils (SAE 10W/40, API service SE) operated in a Toyota 20R engine over a 8000 km period were evaluated (Coates and Setti, 1984). Major absorptions bands (1900 to 1500 cm 1) of the spectra are [cm 1] 1732 (oxidation, carbonyl esters), 1710 (oxidation, carbonyl ketones/acids), 1629 (nitrate esters), 1605 (carboxylates) of used oils. 

The diesel engines oils designated for this service were introduced in 1994 and may also be used when API service category CD is recommended. 

Anonymous, ASME Boiler and Pressure Vessel Code, Section VIII, Div. 1, American Society of Mechanical Engineers, New York, NY, 1980. Anonymous, Heat Exchangers for General Refinery Service, API Standard 660, American Petroleum Institute, Washington, D.C. 

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