FILTERABILITY OF ENGINE OILS AFTER TREATMENT WITH WATER: ASTM D6794
EXPLANATION
Usually some of the combustion products of an internal combustion engine penetrate into the engine lubricant and are retained in it. When the engine is stored over a long period of time after running for a short period of time, the by-products of combustion may be retained in the oil in a liquefied state. Under these circumstances precipitates can form that impair the filterability of the oil next time the engine is run. This test method subjects the test oil and the new oil to the same treatments such that the loss of filterability can be determined. The test method requires that a reference oil also be tested and results reported. Two oils for this purpose are available from ASTM Test Monitoring Center. One oil gives a high data value, and the other gives a low value for this test.
With the use of ASTM TMC reference oils, a laboratory can assess whether their use of this test method gives statistically equivalent results to those obtained by other laboratories.
Also, various agencies require that a laboratory utilize the TMC services in seeking qualification of oils against specifications.
TEST SUMMARY
The test oil is treated with deionized water and is heated to 70° C for 6 h, followed by storage at room temperature. The sample is filtered and the flow rate is calculated determining the engine oil filterability characteristics.
TEST PRECISION
Repeatability: 11.1 %
Reproducibility: 25.4 %
These precision estimates should be used for judging the acceptability of 25 μm filter results. Since there is no accepted reference material suitable for determining the bias for this test method, bias cannot be determined.
