I suspect that my oil pressure switch is leaking oil (which is dripping onto the exhaust), so I've got a replacement (it's a known issue allegedly). I was wondering if anyone knows whether or not I need to drain the oil first ? After all, the oil pressure switch is located under the oil filter on the engine, so surely if I remove it, oil will leak out? Or am I not understanding how the oil pressure switch works ? I watched a video of someone replacing one of these switches on Youtube, but he didn't say anything about draining the oil first.