D664_10 (17a) 04-2018

When applicable, refer to practice D4057, Manual Sampling, or practice D4177, Automatic Sampling, for proper sampling techniques. When sampling used lubricants, the specimen shall be representative of the system sampled and shall be free of contamination from external sources. Agitate used oil samples thoroughly to ensure that any sediment present is homogeneously suspended before analysis, as the sediment can be acidic or basic, or have absorbed acidic or basic material from the sample. When necessary, samples are warmed to aid mixing. As used oil can change appreciably in storage, samples should be tested as soon as possible after removal from the lubricating system. And the dates of sampling and testing, if known, should be noted.