Hey List, how is everybody doing?  And your vans?

I've got a question/concern about my van's cooling system.  About 3 or 4
weeks ago I was about to make a return trip to PSU.  I was looking over
things and noticed the coolant refill tank was bone dry after the van
had sat overnight.  I took off the cap to the expansion tank and it was
completely full.

On my way to PSU, I stopped at Advance and bought a container of Gm's
Dexcool (I think that was the name - the orange stuff).  I added a 50/50
mixture to the max line since the van was warmed up already.  First of
all, is it ok to add Dexcool to the existing green stuff?

After I arrived at PSU, I parked the van where she spends most of her
time while I'm busy with classes.  About two weeks ago, I added a bit
more coolant to the cold van to bring the level just above the min mark.

Yesterday, I drove her and checked the coolant level after about ten
minutes of driving - it was below the min line on the refill tank.  BTW,
I have not seen a coolant leak at all - I park in the same spot and
check regularly.

Can anyone suggest why the refill tank was bone dry, or is it just that
when the coolant level goes down, the refill tank reflects this and not
the expansion tank?  Why, after adding more coolant, did the level
continue to drop.  The only thing I can think of is the maple syrup
smell I get when I run the rear floor heater (I presume the smell is
from coolant leaking into the heater), but would it cause such a
noticeable drop in the coolant level.  Thanks to anyone who can give me
some words of widom.

Mike Korsak