vw heat: the electric fan is/was, from what i understood, to help at idle
and in slow moving traffic ... cause if you could keep the rpm up about
about 2000, you had plenty of heat coming through ... assuming, of course,
that all the other parts were in working order.

smell/oil in heat: check also the valve cover gaskets. if they are leaking,
they'll drip right onto the heat exchangers .... and any rust-holes in the
heat exchangers will let the hot oil stink up the air. (it's how i used to
know when my 1971 bus gaskets needed changing. :)

carb/fuel problems but only at night: check also the voltage regulator. my
old bus would start acting 'funny' at night about every two years, and only
in August ... it was the voltage regulator dying. you can notice that the
headlights are looking dimmer and dimmer and yellower and yellower. it seems
that the heat from the engine compartment, especially in the summers of
alabama, were just too much for it.

and if you do decide to replace the voltage regulator, DISCONNECT THE BATTERY
FIRST!!! i'm serious ... do it! i didn't ... just one time ... and i slipped
and dropped the partially connected regulator, which naturally grounded to
the chassis. ever seen a great big red wire (that runs to the generator)
just 'evaporate' right in front of your eyes? well, it will! luckily, it
didn't polarize anything or hurt the generator ... but it certainly increased
the pucker factor that day! 8*

joel