By Jeffrey Moser For do-it-yourselfers, this is all of the equipment needed to take an oil sample. We ran the engine until it reach operating temperature, removed the dipstick, and fed the tube down the dipstick hole. The tube goes to the female end of the oil pump, which acts like an exhaust port. The sample bottle has a threaded cap that matches the threads on the oil pump, ensuring a tight seal. Pulling back on the plunger sucks the oil from the engine directly into the sample bottle. The bottle should be filled not quite to the top. We then removed, capped, and labeled the bottle.