Obtaining an Oil Sample

Obtaining an Oil Sample

Obtaining fluid samples is relatively simple, but it is important to understand the proper methods for taking a sample to ensure accurate and beneficial results. Sampling methods may vary according to the type of equipment from which the sample is taken. Automotive and mobile applications typically require a vacuum pump, while common industrial applications may provide direct access through a sample valve or system reservoir. A vacuum pump may also be used for industrial applications if a sample valve is not available.

All kits and materials necessary for obtaining an oil sample are outlined on pages 14-15 of the Oil Analyzers User Guide.

Vacuum PumpSampling with a Vacuum Pump

A vacuum pump is used to take samples from a dipstick or non-pressurized system.

To use a vacuum pump, securely attach a sample bottle to the pump. Attach a clean tube to the top of the pump with the tube extended approximately 1 inch into the bottle and tighten the lock ring. Before placing the free end of the tube into the dipstick retaining tube or oil fill port, cut the tip of the hose at a 45-degree angle. This helps prevent the tubing from sealing against the bottom of the oil pan or sump. Pump the plunger until oil flow is consistent and then pump only as needed to maintain consistent flow. The sample bottle should be filled about ¾ full or to its shoulder. Remove the sample bottle from the vacuum pump and tighten the lid securely.

Sampling through a Sample Valve

Some industrial applications have a sampling port through which a sample can be obtained. There are several different styles of sampling valves, including minimess, pitot tubes, push button, ball valves and more. This sampling method requires the equipment be in operation, if possible. If not, the sample should be taken within 30 minutes of shutdown so the oil is warm and to avoid the settling of contaminants. Open the sampling valve and allow a small amount of oil to flush contaminants from the valve into a waste container. Place the sampling bottle under the valve and obtain the sample. The sample bottle should be filled about ¾ full or to its shoulder. Ensure the sample valve is securely closed once the sampling process is complete.

Sampling from a System Reservoir

If collecting a sample through a sample valve is not possible, the equipment's system reservoir can be used. The oil must be drained from the plug for a few moments before the sample is taken so contaminants that have settled around the drain are flushed out. Once the drain has been flushed, place the sample bottle in the oil stream and collect the sample. Using the reservoir drain plug is the least desirable method for obtaining an oil sample because the bottom of the reservoir contains elevated amounts of contaminants. It should be used only when the other options are unavailable.

Mobile Sampling Locations

Appropriate sampling locations for automobiles, light-duty, heavy-duty and over-the-road trucks include the oil dipstick tube, the oil pan drain plug or petcock valve, if one has been installed.

Industrial Sampling LocationIndustrial Sampling Locations

Common sampling locations include the oil reservoir, sampling port and filtration mount. If a vacuum pump is being used, it is best to have the sample tubing extend down into the middle of the reservoir, rather than the top or bottom of the tank. If excess wear is detected in industrial applications, samples can be taken immediately before or after specific components, such as pumps or valves, to help isolate which component is producing excess wear elements.

About Us

Oil Analyzers INC. is a fully equipped oil analysis laboratory staffed by highly trained analysts. Oil Analyzers INC. offers a complete line of oil analysis services, including engine oil analysis, drivetrain oil analysis and industrial lubricant analysis.


Oil Analyzers INC.
1101 Susquehanna Ave.
Superior, WI 54880
Customer Service:
(877) 458-3315