There seems to be no winter 88C thermostat readily available, so I' m thinking of removing the 82c wax capsule from the plastic housing and replace it with a 88c one, here are some pictures. Did someone already try this, or have pictures of a disassembled housing an its internals?
Try going 'non-metric' in your search. I did this using freedom units of measurements and according to the googles OEM #143-0691, THT-018 is a 180-degree (f) thermostat. No idea whether or not it will fit inside the housing for a Prius, or even if it's a real number - and I will not comment on the wisdom of using a non-spec thermostat. Good Luck!
As far as I understand, this was written about Gen2. In 2008, there was no Gen3 with its engine, which has a tendency to overheat the cylinder head. The thermostat provides protection against overheating. Of course, you can throw in 88C as an experiment, but the result may be unpredictable.
