When and How a Used Oil Sample Should be Taken

When
In order to achieve the maximum benefit from an oil analysis program, oil samples must be taken properly at prescribed intervals. Regular sampling at each drain is highly recommended. This establishes a base line for each lube system. Since no two systems are exactly the same, a trend analysis comparing current samples to previous ones give the truest picture of changes in wear patterns that indicate abnormalities in component wear.

How
There are a couple of different methods of properly taking oil samples, the main one being, sampling at drain time. This involves taking a sample of the oil out of the drain plug and following a few simple guidelines.

1. Oil should be in the engine for at least 1000 miles or 20 hours to insure accurate analysis.
2. Oil Should be sampled while system is warm, i.e., as soon as possible after shutdown.
3. To avoid contamination, always clean the area around plug before sampling.
4. Allow approximately two quarts of oil to drain before collecting the sample.
5. Collect the sample directly into the sample bottle. Do not dip the sample bottle into the drain pan.

The second most frequently used method is the sample pump. In this method, a tube is inserted down the dipstick line and oil is drawn into the collection bottle by suction from the pump. Guidelines (a) and (b) should be followed when using this method.

Finally, complete and accurate sample data should be submitted with each sample. This data should include the following:
	- Company name and address - Unit number - System make and model - Miles/hours on system - Miles/hours on oil - Miles/hours since overhaul - Sample Date - Brand and grade of oil used - Oil added (make-up oil) - Person to contact with results

This information is invaluable to the laboratory since it is considered heavily when maintenance recommendations are made.

For example:

Miles or hours since overhaul
A new or newly overhauled machine showing relatively high levels of wear metals in the oil is perfectly normal when break in wear is considered.

Miles or hours on oil
Oil samples with low miles or hours containing high wear metals indicate a high wear condition, whereas the same metal levels at high miles may or may not be considered critical.

Oil added (make-up oil)
Engines using excessive amounts of make-up oil will tend to show lower wear metal levels due to the diluting effect of the make-up oil.