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Engine Oil for your Porsche

Engine Oil Numbers Explained?
To most people Engine oil has become a complex subject to understand. You only have to look at the bottle and you see a vast array of letters and numbers. Choosing the right oil for your Porsche is vital for engine performance, wear characteristics and fuel consumption. But how are we to make the right choice without knowing what the oil terminology means. Fortunately this is standards based industry so there are standards bodies to define and explain the jargon.

So what about those oil numbers

Typically on the front of a bottle or can of engine oil is the viscosity rating of the oil. Viscosity can be thought of as the oils thickness and therefore indicates the ability of the oil to flow. For modern engine oils the viscosity ratings will appear as two numbers separated by a W. Examples include but are no means limited to: 0W30 5W30 10W40 15W50 and 20W50 and so on. These are referred to as multigrade engine oils. Simply put this means the oil contains additives to modify the oils viscosity at certain temperatures. The multigrade oil is essential as the temperature range the oil is exposed to in most vehicles can be wide ranging from cold ambient temperatures in the winter before the vehicle is started up to hot operating temperatures when the vehicle is fully warmed up in hot summer weather and for people reading this in stressful trackday conditions at high RPMs.

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So if we take an example of a muligrade viscosity of 15W50. The first number of the code 15 indicates the lowest operational cold temperature range while the second 50 signifies the highest operational temperature range. For single-grade oils the viscosity is measured at a reference temperature of 100 degrees C in units of mm/s (or the equivalent older units centistokes abbreviated cSt). based on the range of viscosity the oil falls in at that temperature the oil is graded as an SAE number 0 5 10 20 30 40 50 or 60. The higher the viscosity the higher the SAE grade number is. These numbers are also often referred to as the weight of a motor oil. The reference temperature refered to here is meant to approximate the operating temperature to of the engine to which oil is exposed.

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And the letters

The Viscosity rating will often be preceded by SAE which stands for the Society of Automotive Engineers. This is the body which sets the viscosity standards to determine the numbers above. The governing SAE standard is called SAE J300. This "classic" method of defining the "W" rating has since been replaced with a more technical test where a "cold crank simulator" is used at increasingly lowered temps. A 0W oil is tested at W22;35 deg C (W22;31 deg F) a 5W at W22;30 deg C (W22;22 deg F) and a 10W is tested at W22;25 deg C (W22;13 deg F).

W stands for Winter not Weight designating their "winter" or cold-start viscosity at lower temperature.

So now that you understand a little more about engine oil, you should now be in a better position to choose the right oil for your Porsche - or at least understand more about the oil your Porsche deale recommends.

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By: DaveT

Date: 05-11-13

Rated: 0

I didnt't know that "W" stood for Winter. I always thought it meant Weight. You learn something new every day

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