Historically we were taught that 180 was "operating temperature". Anything over that was on the hot side.
GM now installs 195 degree thermostats. Why? Well...Physics dictates that the hotter you operate an engine, the more efficient it is, to an extent...overheating is always bad. The hotter you can run an engine, the more complete the combustion, the less emission, less wasted fuel, more bang per ounce of gasoline etc....
So...if your 98 is showing between 200 & 210...you're okay. Many folks replace the 195 t-stat with a 180 because (like me) they think YEOW! I am borderline overheating.
But the down side of that is that the computer knows what the engine is supposed to do...and if you don't let it get up to the operating temperature that the computer thinks you are supposed to have...the computer thinks that you are still warming up the motor and chokes the engine etc...
If you are not overheating...leave it alone. If it scares you, replace the tstat with a 180...and prepare to suffer fuel economy!
