So, I have been continuing to drive the car - and even with a 200mi trip, the gauge still does not go above 1/2way. I also notice that once the car has been warm for about 30 minutes, the fluctuations tend to be less noticable, if at all - the gauge stays more at it's normal position, just below halfway.

I have had no other symptoms, or weirdness in terms of temperature. It seems that the thermostat may be sticking a little, especially when the engine is not fully warmed up. Knowing that over time, this will only get worse, I do plan to replace the thermostat before the end of the year.

Now, that being said, do I need any other parts besides what comes with the thermostat from the dealer or mitsubishiparts.net? (RTV sealant, gasket, etc?) I have been told different things - and want to make sure I do it right.

Thanks!