Ex owner told that all filters and oil has been changed before I bought the tractor. If that is true, then oil and filters have been changed less that 150 hours ago. Of course I cannot be sure is it true. Oil looked clear when I changed that 150m filter.
According to manual that warning light is for that particular filter but don't know is it measuring pressure in the whole system, so is also problems in other filters affecting to the light.
Have to change them all and the oil but would not like to do it "just in case" because it costs like 800€.