I have a 2000 Cherokee Sport 4.0L w/ 189k miles and recently (past couple weeks) the oil pressure gauge has been maxing out at 80psi. When the engine is cold it is constantly maxed out but once it warms up the pressure drops to ~50psi when stopped and idling then shoots back to 80 as soon as you start giving it gas. I just changed the oil and filter last weekend and it has the correct oil level. I was thinking it could possibly be a defective gauge but I'm not sure if that could be the case seeing as the pressure drops to a semi-normal range once it's warmed up and idling?
Any ideas would be greatly appreciated!