Making sense of all those letters and numbers
Pick up any pack of oil and read the label. Printed there will be a series of abbreviations that tell you the performance attributes of the pack’s mysterious, brown slippery contents.
API (American Petroleum Institute) specifications are perhaps the most widely quoted. Prior to 1930, the API introduced a system of engine oil specifications. “S” denoted a petrol engine (think spark) and “C” denoted a diesel engine (think compression) followed by a second letter. As the second letter advances along the alphabet, so too do the performance requirements. API SA was the first and has progressed to API SN, introduced in 2011.
The table below lists the year progressive API standards were introduced. The bottom row lists the power output of the six-cylinder four-litre Ford Falcon engine. This engine configuration was relatively unchanged, but power output increased by over 50 percent.
In 1972, oil drain intervals were 2,500 miles (4,000km), and every petrol station had an oil bowser in the forecourt. In the following years, emission controls tightened, and exhaust gas recirculation was introduced.
This meant higher temperatures and more exhaust gases for the engine and its oil to cope with. Engine designs changed, drain intervals extended, and sump sizes got smaller. The API system provided a performance standard that engine and lubricant manufacturers could use as a baseline.
ACEA – Association des Constructeurs Européens d’Automobiles – is the European system for lubricant classification. It uses a combination of letters and numbers to designate application and performance level.
Engine type followed by Technical Performance Level 1, 2, 3, 4, 5, 7, 9. A: Petrol. B: Light diesel. E: Heavy duty diesel. C: Catalyst compatible oil. Stated ACEA specifications often include more than one designation. As an example ACEA A3/B4 is a specification for a petrol and a light diesel engine. Technical performance level does not necessarily increase with the higher number. ACEA A1/B1 has better fuel saving performance than ACEA A3/B4, but the latter has extended drain capabilities.
On top of API and ACEA specifications will be OEM standards. These are the most important if you want the correct lubricant for your vehicle. However, not all OEM’s have lubricant standards but will instead specify that a lubricant must meet a certain API or ACEA standard.
A typical example of the specifications listed on a pack is those on eni i-Sint CRDI 5W-40. It states ACEA, American Petroleum Institute and specific OEM standards for BMW, Mercedes-Benz, Volkswagen and Porsche. All reputable lubricant manufacturers will state the standards that their products meet in a format similar to this.
As you have seen, there is a method to the madness. Understanding and appreciating what these numbers and letters are telling you are the key to ensuring the correct oil is used in the correct application.
For further information on eni lubricants visit: www.transdiesel.com