Product Tested

front label

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back label

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Company and Product Information

Corporate Office:
1500 Vally Rd
Wayne, NJ 07470


 Castrol is one of the world’s leading manufacturers and marketers of premium lubricating oils, greases, metalworking fluids, control fluids and related services to automotive,  manufacturing, mining, marine, and oil exploration and production customers across the world. Castrol employs over 7,500 people, it operates directly in more than 80 countries, and is represented by over 2,000 third party distributors. Part of the BP group, the company is headquartered in the UK. 

The brand represents over 100 years’ experience in ‘liquid engineering’: producing advanced lubricants for a wide range of applications, from manufacturing processes and metalworking to mining, shipping and marine activities and energy production.


The Petroleum Quality Institute of America (PQIA) is an independent resource for information and insights on the quality of lubricants in the marketplace. Our mission is to serve the consumer of lubricants by randomly sampling and independently testing lubricants taken from the field. Test results are posted along with the brand names on the PQIA website. This webpage provides an analysis on the brand detailed below.

The following are the test results for the sample examined.

Castrol GTX
SAE 10W-40 Motor Oil

Product: Castrol GTX
Viscosity Grade: SAE 10W-40
Labeling: API SN/ILSAC GF-5

Marketed by: BP LUBRICANTS USA, INC., Wayne, NJ

Purchased at: Washington, D.C.

Date of purchase: 7/1/2015


Website(s): www.castrol.com/us 

Test Results and Assessment:

The results of the tests conducted on this sample meet the SAE J300 specifications for the SAE Viscosity Grade listed on the product label, and are consistent with the listed API Service Categories.


bottle icon Physical Properties pass
Elemental Analysis pass
Labeling warning

Note: Although laboratory tests alone cannot be used to establish if engine oil meets an API Service Category, they can be used to determine if it doesn't.

PHYSICAL TESTS (click for test details) - a Standard Castrol GTX
TBN, mg KOH/g (ASTM D2896) 7.3
Viscosity @ 100ºC, cSt (ASTM D445) 12.5 to 16.3 14.5
Viscosity @40ºC, cSt (ASTM D445) 99.9
Viscosity Index (ASTM D2270) 150
Viscosity @-25ºC mPa s (cP) (ASTM D5293) 7,000 Max 6031
Volatility, mass % loss, 1 hr, @ 250ºC (ASTM D5800) 13 Max -c 11.0
ELEMENTAL ANALYSIS (click for test details) - a, b
Calcium 2332
Magnesium 10
Phosphorus, ppm 600 792
Zinc, ppm 860
Molybdenum,  ppm 85
Barium, ppm <1
Boron, ppm 166
Silicon, ppm 7
Potassium, ppm <5
Manganese, ppm <1
Titanium, ppm <1
Copper, ppm <1
Sodium, ppm <5
Vanadium, ppm <1
Silver, ppm <1
Aluminum, ppm 4
Chromium, ppm <1
Iron, ppm <1
Nickel, ppm <1
Lead, ppm <1
Antimony, ppm <1
Tin, ppm <1
  1. Standards, shown in yellow are established by API, SAE and others.
  2. Test Method for metal analysis is ASTM D5185.
  3. This specification is expressed to two significant figures, therefore results up to 15.5 are considered on specification.