Originally Posted by
harbor
Both fluids are synthetic and meet the 11S spec, so topping off with Prestone should be fine. If you're not sure what fluid is currently in your car, you may want to consider using a turkey baster/suction pump to suck out the reservoir and top off with Prestone.
If it were mine, however, I'd stick with Pentosin. Just a personal preference.
Do we know if the color of the Pentosin chf-11s was ever changed during manufacturing? What's in the reservoir now is sort of a light orange color.