ASTM D4859 Lubricants for Two-Stroke-Cycle Spark-Ignition Gasoline Engines-TC
6. Pass-Fail Criteria
6.1 All Tests - The performance of the candidate oil shall be as good as, within the tolerance allowed, or better than that of the benchmark reference oil. Rating procedures are given in the test methods.
6.2 Ring Sticking and Deposit Test:
6.2.1 In this test two runs are normally made, exchanging the oils between cylinders after the first run and the means of the ratings for the candidate oil and reference oil are compared, except that a pass may be given to the candidate oil without making the second run if all conditions stated in 6.2.8 are met. If the first run of a two run test is conducted with oversize hardware, then the second run shall be conducted on oversize hardware. Conversely, it the first run of a two run test is conducted on standard size hardware, then the second run of the two part test shall also be run using standard size hardware.
6.2.2 The occurrence of scuff or seizure in any part of the test engine, with the candidate oil, shall require the test or current portion of Test Method D4857, to be rerun. If scuff or seizure occurs again with the candidate oil, the test shall be terminated as a failure unless it can be established that the failures are caused by some deficiency of the equipment. In this case, after correction, the test may be rerun. The occurrence of scuffing or hot stuck rings in the reference oil cylinder shall not result in test invalidation.
6.2.3 Second Ring Sticking - The mean rating of the second rings of the candidate oil pistons shall be not more than 0.5 merit number below that of the rings run on the 600 reference oil. Under no circumstances shall there be any evidence of hot stuck rings in the candidate oil cylinder.
6.2.4 Piston Skirt Varnish - The average piston varnish rating of a candidate oil shall be not more than 0.5 merit number below that of the 600 benchmark reference oil.
6.2.5 Spark Plug Fouling or Bridging - Not more than two more occurrences per complete test (2 runs) with the candidate oil than with the 600 benchmark reference oil.
6.2.6 Preignition - More than one occurrence of major preignition in the candidate oil cylinder shall constitute a failure.
6.2.7 Exhaust Port Blocking - The percentage of the exhaust port area blocked by deposits in either run of the test shall be not more than 10 % greater for the candidate oil than for the 600 benchmark reference oil.
6.2.8 Early Pass Criterion - A test may be terminated after the first run with a pass for the candidate oil if the following conditions all exist:
6.2.8.1 Second ring sticking merit rating for the candidate oil is 9.0 or better, regardless of the second ring sticking performance of the benchmark reference oil, which can occasionally exhibit hot stuck rings.
6.2.8.2 The piston varnish rating for the candidate oil is absolutely (without consideration of tolerance) equal to or better than that for the benchmark reference oil.
6.2.8.3 There has been no incidence of preignition, major or minor.
6.2.8.4 Exhaust port blocking for the candidate oil is not more than 5 % greater than for the 600 benchmark reference oil.
6.2.8.5 There has been not more than one incidence of plug fouling with the candidate oil.
6.2.8.6 There is no evidence of scuff, hot stuck rings, or other lubricant related damage in the candidate oil cylinder.
6.2.9 Early Fail Criterion - A candidate oil test shall be rated as a failure, and may be terminated after the first run, if there has been any incidence in the candidate oil cylinder of hot stuck rings, major preignition, or excessive port blockage as defined in 6.2.7.
6.3 Lubricity Test - The average torque drop observed for the candidate oil shall be equal to or less than that for the benchmark reference oil ASTM 600. See the Test Method D4863 (Annex A4) for the method of computation.
6.4 Preignition Test:
6.4.1 Major Preignition - Not more than 1 major preignition with the candidate oil.
6.4.2 Minor Preignition - The number of minor preignitions is not a pass-fail criterion due to poor reproducibility, but an oil showing six or more minor preignitions involving a temperature increase of 7°C (12°F) or more but less than 10°C (18°F) shall be retested. If the criterion of 6.4.1 is met on the second test the oil passes.
6.4.3 Other Plug Malfunctions - Not more than one occurrence of plug fouling or plug whiskering with the candidate oil.
7. Keywords
7.1 API TC; engine oil; TC; two-cycle; two stroke; two-stroke cycle engine oil; two-stroke cycle engine oil specification
