I have no issues with the oil cooler on my CK30. I have read in other posts on this site that some of the earlier machines had issues. Apparently the early machines the oil lines were ridged plumbed to the cooler and caused some cracking. The later machines, mine included, have a short, 5inch, length of rubber hose to isolate the cooler from engine vibrations. The post I read, can't find it now, had pictures showing old rigid style and the new 'flex' style.