Red Line Water Wetter is widely used but can compromise your watercooling component, it contain a thick oil that tend to separate from the mix due to the very fast pump impeler rotation enthusiast use in their watercooling setups. Once that thick oil has been shaken off from the mix, it will form long tendrils that will stick inside the waterblock, the radiator and tubing.
Try to find a similar product that does'nt contain any oil or lubricants and make sure that you are not using too much of the stuff, higher concentration have a negative impact on the thermal transfer.
I stop using additives made for the automotive industry after I found a sticky film inside my tubing, I flushed the system with methanol to dissolve as much of it as I could and tried Swiftech's HyrdX instead, so far so good, I am even seeing lower full load and idle temps.
C-Systems CSP 750 in-line pump
HW Labs Black Ice Micro rad
Danger Den TDX Waterblock
Kuri Tec Clear Vynil 1/2" ID tubing
Watercooled Mobile Barton 2500+ @ 2.6GHz (200MHz x 12.5)
Abit NF7-S V2.0
2x 512MB of Samsung TCC4
Sapphire Radeon 9700 128MB @ 360/310
2x Maxtor 40GB 7200RPM RAID-0