My car's 6 CD changer was intermittently losing and skipping sound in the left channel.  Because the right channel remained OK I did not think it might be a dirt or cleaning issue.  I figured both left and right channels should be affected.  I lamented over my player for weeks because I could ill-afford whatever the cost might have been to even have a tech check out a fancy Bose CD player embedded in the dashboard of a car.  I gradually listened to my player less and less because knowing the sound problem just made me more sensitive to the imperfections when they occurred. Finally I figured, what have I got to lose just to find out if this is a "dirt" problem?  $8 bucks compared to all other alternatives was a small price to pay. Hola macarola...I'll be darned if this disc didn't cure my player immediately! I wish I had given this thing a shot a lot sooner.  Technically there was problem though.  The instructions say the CD has sound.  It's supposed to alert you when it's done cleaning or whatever.  My product produced no sound at any time.  I inserted it into my player and my dash display simply blinked indicating a playing disc. It ran, and ran, and ran.  It never alerted me in any way that the process was over nor did it stop running on its own.  I simply had to eject it. I deducted one star only because of this "technicality".