I searched autozone website. "No related information found for engine ice." I'm just
using a standard antifreeze mixed 50/50. Haven't tried anything else in the RC.
It's more than a coolant brand. not full enuf, blockage somewhere, thermostats rarely stick closed so ...
Anyway, I guess i would say, start with looking for any leaks, change out coolant and make sure your overflow container is working properly, if you see any crud in the bottom, take it off and clean it out real good and purge the hose too. That's what I did to mine and it worked pretty good.
I wasn't to familiar with the RC when I did my coolant flush, but the service manual is real easy to follow and I did it more thouroughly as a result.
John, 2000 RC51 #000100