Scott, my impression is that commerce will make whatever people will buy.  Some folks get to thinking that if their engine overheats, putting in a cooler thermostat will help.  It won't.  The thermostat is there to raise the temperature to the stated level.  If it is working correctly, it opens once that temperature is reached.  The engine can still overheat, but not because the thermostat is the stock 87 C thermostat.  Overheating is higher than 87 C.  The 80 C thermostat will open at 80 C, but it won't keep the engine from overheating if there is a problem otherwise, either.  If the engine is overheating, there is a problem other than too hot a thermostat, and a cooler one will not help.  And the reason stock thermostats are 87 C is because that's the temperature at which the engine runs best (might actually run better a little hotter, but 87 works, while 80 is too cool).

Some experts (I'm not one) may have a different explanation, or may even disagree.

---- Scott Chapman <scott_list@MISCHKO.COM> wrote:
> I see that there's lower temp thermostats avaialble for the Westy.
> What's the use of a lower temp thermostat?  Stock is 87 and these are 80
>  IIRC.

--
David McNeely