So about a year ago the temperature gauge on my dash started spiking up
and then would go down real quick. Sometimes it stays up for a while
and sometimes it's just up for a quick second. Sometimes it just jumps
a little and sometimes it goes all the way into the red. It happens in
cold and hot weather, with the AC on or off and with the Heat on or
off.  It happens at high speeds and in traffic. On a hot summer day it
happened two seconds after I turned on the car.

I recently had my heater core replaced since it was leaking. This
temperature gauge problem was happening a year before the heater core
broke. During that visit the mechanic also replaced the Thermostat and
flushed & refilled the coolant.  I was hoping that one of these things
would solve the problem but it did not.

So this is two shops that have looked at the car and haven't had any
idea. It's also hard for them to test since it happens randomly.

I've tried a ton of things to get it to go back down such as turning
off the heat or turning it way up. Nothing I do seems to help. Knowing
little about cars I've been thinking that perhaps its the fan in the
engine that it's always turning on all the time, and then just kicks
in. And yes there is oil and coolant in the car.

Well I'm posting again about my 89 Camry since I received such good
information last time. Thanks in advance.