The finder indicates available capacity is 140,53GB. Disk Utility shows only 123,84 GB, in the rMBP in my signature. Almost 17GB difference!!! I had read earlier somewhere, that there will always be some difference between these two readings (and the one in Disc Utility is the one that should be trusted...) but is this much normal in a 256GB Flash Storage Drive with Yosemite? Is there any safe and free way that I may get rid of any junk files, which should be there in some amount? Thanks for any assistance.