The filled sample racks are heated in an oven at 60 °C along with their transparent OELCHECK bottles for at least 20 minutes "upside down" i. e. standing on their lids. Any foreign substances in the oil fall to the white inner surface of the lid and are easily recognisable when the bottle is turned back and opened.
Immediately after the sample bottle is quickly turned on its head and opened, attention is turned to the white inner surface of the lid seal for diagnostic purposes. Abnormalities in the lubricant can be recognized as particles.
Photos are then taken of the inside of the lid and the well-lit opened sample bottle together using a camera and assigned to the sample number.
After the photograph is taken, an initial assessment is made of the appearance of the oil sample and any sediments in the lid by means of a comparative estimate.