I find it hard to believe that the Vanagon Myth, about an improper
coolant mixture will cause the blinking light to go on, persists.

In 18 years I've owned 5 running Vanagons (currently have 3 1/2) and
numerous times, whether due to emergency or to flushing the coolant
systems, I've run the engines with straight water (NO antifreeze) and
have gotten no blinking lights.

I'd say the probes are about as sensitive as the ones in a Westy fresh
water tank ... the ones that light the water level lights.

Mike