Here's a question for the sage Vanagon mechanical volks out there:

Anyone experience lower mileage after installing a new 87 degree
(stock) thermostat? The average hwy MPG over the same 1300 mile trip
went from 18.5 down to less than 16 since the new thermo was
installed. The engine is running great and just passed smog with
flying colors (with the new thermo). The temp gauge reads just above
the LED with the new thermo (the old 80 degree thermo (lower than
stock, but seems to be a common choice here in CA) ran just below the
LED before it failed). The engine heats up really fast and the heater
works much better (hotter & quicker). I would have thought these
conditions would bode well for better mpg and a cleaner burning
engine, but now I am skeptical. Does a hotter-running engine use more
gas or could there be another cause that happened at the same time?

Thanks in advance...

Keith
90 Syncro westy VikingWagen