Not in a 912S RV12 but....
I have been running Evans in two different 912 UL engines (300+hrs and 150hrs+) for about 4 years. It warms up quicker and seems to reach an operating temperature about 15F to 20F warmer than with the original water/antifreeze mix that was running in the engines for their first ~500hrs. It doesn't build up much if any system pressure, I figure if I spring a leak it should take longer to lose all the coolant. Been operating in temps from 90F+ to 0F. No other side effects noted.
