We have a 7800 ICP-MS with a MS40+ vacuum pump. Prior to our PM in ~September of this year, I noticed the pump was overdue for an oil change. Our oil was changed during the PM, but I noticed the color of the oil through the window seemed much darker than it should have following an oil change. Fast forward to today, I changed the oil and prior to turning the vacuum back on, noticed the oil was very clear in the window. Once I turned the pump on, the oil appeared to be just as dark as it was when I started.
I wasn't sure if you only get the best visual of the oil during shutdown, or we have an incredibly dirty vacuum pump that might need another oil change right away to flush out the pump.
Any advice would be appreciated, thanks!