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TOP TIER Detergent Gasoline Deposit Control Performance Standard Revision C-February 2015

1.1 Performance Description.   This document describes the deposit control performance of an unleaded gasoline at the retail level that minimizes deposits on fuel injectors, intake valves, and combustion chambers.

All performance testing must be conducted at an independent, ISO 17025 accredited laboratory.

3. Definitions

3.1 A2LA – the American Association for Laboratory Accreditation

3.2 Independent Laboratory – a mechanical and/or chemical testing organization not associated with the business entity seeking TOP TIER Detergent Gasoline status, accredited by the A2LA for technical competence in mechanical and chemical testing in accordance with the latest version of ISO 17025, General Requirements for the Competence of Testing and Calibration Laboratories.

4. Standards.

4.1 Retail Gasoline Performance Standards.   The deposit control performance of unleaded gasoline conforming to section 4 of this document shall be met at the retail level in all grades of gasoline sold by a fuel company in all marketing areas of a selected nation. In addition, conformance to the standards shall mean gasoline sold in the selected nation shall not contain metallic additives, including methylcyclopentadienyl manganese tricarbonyl (MMT).

4.2 Deposit Control Additive Requirements.   The deposit control additive used to meet the performance Standards described in 4.3 shall meet the substantially similar definition under Section 211(f) of the Clean Air Act. Also, the additive shall be certified to have met the minimum deposit control requirements established by the U.S. Environmental Protection Agency (EPA) in 40 CFR Part 80. Lastly, the additive shall be registered with the EPA in accordance with 40 CFR Part 79.

4.3 Deposit Control Initial Performance Standard.   All performance testing and fuel composition analysis shall be conducted by an Independent Laboratory. Initial deposit control performance shall be demonstrated using the tests shown below.

4.3.1 Intake Valve Keep Clean Initial Performance Standard.

4.3.1.1 Test Method.   Intake valve deposit (IVD) keep clean performance shall be demonstrated using ASTM D 6201, Standard Test Method for Dynamometer Evaluation of Unleaded Spark-Ignition Engine Fuel for Intake Valve Deposit Formation. Tests demonstrating base fuel minimum deposit level (4.3.1.2) and additive performance (4.3.1.3) shall be conducted using the same engine block and cylinder head. All results shall be derived from operationally valid tests in accordance with the test validation criteria of ASTM D 6201. IVD results shall be reported for individual valves and as an average of all valves.

4.3.1.2 Base Fuel.   The base fuel shall conform to ASTM D 4814 and shall contain commercial fuel grade ethanol conforming to ASTM D 4806. All gasoline blend stocks used to formulate the base fuel shall be representative of normal U.S. refinery operations and shall be derived from conversion units downstream of distillation. Butanes and pentanes are allowed for vapor pressure adjustment. The use of chemical streams is prohibited. The base fuel shall have the following specific properties after the addition of ethanol:

  1. Contain nominally 10.0% ± 1% by volume ethanol as measured by ASTM D 4815 or D 5845.
  2. Contain no less than 8 volume percent olefins as measured by ASTM D 1319 or D 6729.
  3. Contain no less than 28 volume percent aromatics as measured by ASTM D 1319 or D 6729.
  4. Contain no more than 80 mg/kg sulfur as measured by ASTM D 2622 or D 5453.
  5. Produce a 90% evaporated distillation temperature no less than 290°F as measured by ASTM D86.
  6. Produce IVD no less than 500 mg averaged over all intake valves.
  7. A Certificate of Analysis showing both the detailed test fuel composition results and source should accompany the additive results package. This certificate should also contain the unwashed and washed gum level of the base fuel according to ASTM D381.

4.3.1.3 Demonstration of Performance.   The base fuel from 4.3.1.2 shall contain enough deposit control additive such that IVD is no more than 50 mg averaged over all intake valves. Results for individual valves and an average shall be reported. The unwashed gum level of the fuel containing deposit control additive shall be determined according to ASTM D 381 and reported.

4.3.2 Combustion Chamber Deposit Initial Performance Standard.  

4.3.2.1 Test Method.  Combustion chamber deposits (CCD) shall be collected and weighed along with IVD using ASTM D 6201, Standard Test Method for Dynamometer Evaluation of Unleaded Spark-Ignition Engine Fuel for Intake Valve Deposit Formation. ASTM D 6201 does not contain a procedure for collecting and measuring CCD. Adapting a scrape and weigh procedure developed by CARB is recommended (see referenced test method dated March 12, 1999). Results for individual cylinders and an average shall be reported.

4.3.2.2 Base Fuel.  Combustion chamber deposits shall be measured for the base fuel from 4.3.1.2.

4.3.2.3 Demonstration of Performance.  The base fuel from 4.3.1.2 treated with additive at the concentration meeting the standard found in 4.3.1.3 shall not result in more than 140% of the average CCD weight for the base fuel without additive.

4.3.3 Intake Valve Sticking Initial Performance Standard.  

4.3.3.1 Test Method.   Intake valve sticking tendency shall be determined using either the 1.9 L Volkswagen engine (Wasserboxer according to CEC F-16-T-96) or the 5.0 L 1990-95 General Motors V-8 engine (SWRI IVS test). Two options are available for demonstrating intake valve sticking tendency.

4.3.3.2 Option 1.   The valve-sticking tendency of the test fuel by itself will not have to be demonstrated prior to testing the candidate additive. The following shall be required of all tests:

  1. Test fuel shall be either the same as in 4.3.1.2 or CEC valve sticking reference fuel.
  2. Concentration of deposit control additive in the test fuel shall be at least twice the amount determined in 4.3.4.1.
  3. Test temperature shall be -20°C.
  4. Three 16-hr cold soak cycles, each followed by a compression pressure check, shall constitute a complete test.

4.3.3.2.1 Demonstration of Performance   A pass shall result in no stuck valves during any of the three cold starts. A stuck valve is defined as one in which the cylinder pressure is less than 80% of the normal average cylinder compression pressure.

4.3.3.3 Option 2.  The valve-sticking tendency of the test fuel together with an additive known to cause valve sticking shall be demonstrated prior to testing the candidate additive. The following shall be required of all tests:

  1. Test fuel shall be either the same as in 4.3.1.2 or CEC valve sticking test reference fuel.
  2. An additive known to cause valve sticking shall be selected, and, when blended into test fuel, shall demonstrate valve sticking tendency as follows: (a) for the Volkswagen engine, at least two valves shall be stuck; (b) for the GM engine, at least three valves shall be stuck.
  3. Tests demonstrating performance of the candidate additive shall be conducted at a concentration that is at least three times the amount determined in 4.3.1.3
  4. Test temperature shall be -20°C.
  5. One 16-hr cold soak cycle followed by a compression pressure check shall constitute a complete test.

4.3.3.3.1 Demonstration of Performance.  A pass shall result in no stuck valves during the cold start. A stuck valve is defined as one in which cylinder compression is less than 80% of the normal average cylinder compression pressure.

5. Process to Attain TOP TIER Detergent Gasoline Status.   

5.1 Submission of Test Results.  A fuel company desiring TOP TIER Detergent Gasoline status shall forward the test results issued by the Independent Laboratory ("Test Results") to the following address:
Jill Cummings
GM Powertrain Fuels & Lubricants
3300 General Motors Road
Bldg. 42A
Milford, MI 48380-3726

5.2 Notification of receipt.  The Test Results shall be reviewed by GM Powertrain and, if deemed acceptable in its sole discretion, the fuel company will be provided a TOP TIER License Agreement for their execution. Only upon complete execution of the TOP TIER License Agreement by both the fuel company and GM shall the fuel company be entitled to begin use the TOP TIER name in connection with the distribution, promotion and sale of their gasoline, pursuant to the terms and conditions of the TOP TIER License Agreement.

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This technical document describes the deposit control performance of unleaded gasoline at the retail level that minimizes deposits on fuel injectors, intake valves, and combustion chambers.