Petroleum Quality Institute of America

The Petroleum Quality Institute of America (PQIA) is an independent resource for information and insights on the quality and performance of lubricants in the marketplace.  Our mission is to serve the consumer of lubricants by reporting on the quality and integrity of lubricants in themarketplace.






Royal Purple, API SL, SAE 10W-30

Royal Purple Inc.


Purchased in: Auto Zone, Holly Springs, MS

Date of purchase: 10-5-2011







All tests conducted on this sample meet the specifications for SAE 10W-30 and are consistent with API SL engine oil.








The ranges and averages shown in the table below are for the latest specification (API SN GF-5).

Click here for more on API Service Categories.




PHYSICAL TESTS Standard/ranges-b Average-e    Royal Purple
 TBN, mg KOH/g, (ASTM D2896)   7.2    12.7
 Viscosity @ 100ºC, cSt, (ASTM D445) 9.3 to 12.5 10.5    11.46
 Viscosity @ 40ºC, cSt, ASTM D445   N/A    71.17
 Viscosity Index (ASTM D2270)   N/A    155
 Viscosity @ -25ºC mPa s (cP) (ASTM D5293) 7,000 Max N/A    4,156
 Volatility, mass % loss, 1 hr, @ 250ºC (ASTM D5800)   14.2   9.8
    Nitrogen μg/g (ASTM D-5762)   804    3,321
    Calcium   2,051    2,271
    Magnesium, ppm   12    1,181
    Phosphorus,  ppm   1,000 max 703   808
    Zinc, ppm   791   876
    Molybdenum,  ppm   60    152
    Barium, ppm   <1    <1
  Additives and/or others
    Boron,  ppm   79    20
    Silicon,  ppm-d     6
    Potassium, ppm   11    9
    Manganese, ppm   <!1    <1
    Titanium, ppm   <1    <1
    Sulfur, ppm   2,785    13,060
    Copper, ppm   <1    <1
    Sodium, ppm   172    <5
    Vanadium, ppm   <1    <1
    Silver, ppm   <1    <1
    Aluminum, ppm     4
    Chromium, ppm   <1    <1
    Iron, ppm   <1    3
    Nickel, ppm   <1    <1
    Lead, ppm   <1    <1
    Antimony, ppm   <!    <1
    Tin, ppm   <1    <1

a- Click here for product label.

b- Standards, shown in orange, are established by API, SAE and others.

c-Test Method for metal analysis is ASTM ASTM D5185.

d- Although silicon is used as an antifoam additive in lubricants, concentrations above 7ppm have been linked to contamination from abrasive material,

e- Average of the 10 major brands of API SN ILSAC GF-5 (SAE 5W-30) tested. Click here for brands.


Royal Purple
The American Petroleum Institute sets forth a number of laboratory and engine tests required to meet an API SN ILSAC GF-5  performance specification. Although laboratory tests alone cannot be used to establish if an engine oil meets API SN, they can be used to determine if it doesn't.

The following is a comparison of the test results for the sample of Royal Purple tested with the API SN ILSAC GF-5 requirements.


The viscometrics of meets the required targets for an SAE 10W-30.

Viscosity @ 100șC, cSt, (ASTM D445)
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 Viscosity @ -25șC mPa s (cP) (ASTM D5293)
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Click here for more on chart and Viscosity@100șC,cSt                Click here for about chart and Viscosity @ -30șC


Volatility Phosphorus

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Click here for more on chart and Volatilty     Click here for more on chart and phosphorus