Hi,

It seems like I need to replace the thermostat on my 1991 2.1 L Westfalia.

It seems straight forward enough, though as Scott pointed out, perhaps
there will be a problem getting the plastic housing off.  I can deal
with that...

What is the best way to minimize the coolant loss while I'm replacing
the thermostat?  I was kind of thinking of putting the back of the van
up on ramps to get the housing as high as possible to reduce what would
drain from the radiator?  Does this make sense?  or should I just drain
the system & start from scratch.

Also, would the engine running "cool" affect the gas mileage?  I know
there's a temperature sensor (Temp II?) that feeds the coolant
temperature to the ECU, but have no idea what the threshold is, or even
what the input to the ECU accomplishes.  I would assume it's kind of
like a choke on old carborated engines, but not too sure. It seems like
I've been getting poorer fuel economy with the last 4 or 5 tanks & was
wondering if there could be a correlation between that & the engine
running cooler.

Thanks,
Steve W.