Floating is normal, but you probably want the needle to always stay more
or less in the middle of the gauge.  If it's at the lower quadrant of the
normal (non-red) range, the engine will run less efficiently.  If it's in
the upper quadrant, the engine will not last as long.

I'd check your fan and your thermostat before doing anything else.
--scott

On Mar 10, 8:51 pm, gjs1...@gmail.com wrote:

This used to be more common than it is today.  Today's engines/
thermostats do an excellent job in holding water at a specific
temperature.  They used to float around a lot. I had a couple of
somewhat underpowered cars (both straight sixes) that had a
temperature gauge that acted as a rate of climb indicator.  Going up
mountains or long grades the temp would climb quite high, then drop
off as we started down hill.

 Most cars in nineties and current decade control quite closely
(tight servo system). I do get concerned when a modern car has a
fluctuating temp. I would just keep an eye on it, and if it starts to
get too hot, first step would be replacing thermostat.

You know, I got the same smells my 91 and replaced the heater core.
Pressure tested the old  core and it held 30 psi for weeks.
I figure the hose clamps may have been leaking sporadically from
thermal cycling.

Fluctuating needle is normal.
The temp rises until the fan turns on.
Fan stays on until the temp drops and turns fan off.
Cycle repeats.
Totally normal.

91 Topaz with 240,000kms.

Bulletproof motor imho.