1998 Chevrolet S10 ZR2. Owned since new. Never let anything but water or Dex into the radiator and tank. Dex replaced once prior in full. This was approximately 2002. I then did a suck out and refill in the radiator in 2006. The system works fine. I did the TSB to replace the OEM radiator cap, as this is one of the 45 degree radiator necks that is notorious for letting air in and causing gunk. Heat works great. The pic is kind of lousy, but overall, it is super clean, not a hint of dex sludge, and the finned area looks pristine... I just took a quick shot with dirty hands, but it looks better in real life!