Which of the following methods can improve oil sample collection accuracy?

Sampling after an oil change is a method that can greatly enhance the accuracy of oil sample collection. When oil is changed, it removes old, degraded oil and contaminants that may have accumulated over time. By collecting samples immediately after a new oil has been introduced into the system, you are getting a representative sample of the fresh oil that has been added, which can provide valuable baseline data on the new lubricant's condition.

This practice allows for more accurate assessments of the oil's properties, such as viscosity, cleanliness, and additive levels. Additionally, it can be useful for comparing the performance of different oils and ensuring the new oil meets the required specifications. Collecting a sample post-change can help in identifying any immediate issues with the oil or the lubrication system, and it sets a standard for evaluating the oil's performance over time.

In contrast, sampling without flushing the line may introduce contaminants from the lines into the sample. Sampling from the top of the reservoir can lead to a non-representative sample because lighter contaminants may float on the surface, while heavier sediments settle at the bottom. Sampling from the side of the container can also cause inaccuracies, particularly if there are stratifications in the oil or if the sample does not reflect the entire fluid condition of the reservoir.