A liquid filled gauge is good only if the inside movement is vented to the atmosphere. Most automotive type gauges are not vented. The atmospheric pressure in the gauge can cause significant errors in low pressure gauges. The outside barometric pressure and temperature changes make them less accurate. They were designed to give stable reading moreso than accurate readings. They are used on pumps and equipment that have extreme vibrations. An accurate gauge will be accessible from the outside so it can be adjusted during calibration. Most automotive gauges are considered disposable.