Could be a problem with an oil seal, or over filled.
Oil seals in the head ( valve seals ) or oil getting past the piston rings.
Check the oil level first. If it's high, its probably pushing past the rings. I did that in mine when I first fitted it!
Lucky it was sorted quickly.
Check the oil temperature before fitting an oil cooler kit.
I have an oil temp gauge with the sender in the sump.
My temp rarely goes over 80degree's and I've never seen it over 100.
If it's often over 80. I.e. 90+, get a cooler otherwise it's not needed.
Jason.