oil leak

A while ago probably more than 6-8 months ago one of my case fans leaked/sprayed oil in my pc, some of it got on my gpu mostly on the backplate. I recently decided to see if any got under the backplate and I found some of it underneath by the thermal pads. I don't know if I should clean it or...

Hi, i just noticed some kind of leak on my motherboard. Should i turn off my pc immediately and try to clean it or is it ok to just leave it as is? What could cause this to happen?