Running a little warm?
 

I noticed in the last 500 or so miles that I had my Monte is this..Runs a little warm? Could be wrong but the three Impalas with the same 3.5 never would go over halfway mark on the temp gauge.

Anyways I do notice it when I am on the freeway, going 70-80 mph it will start to creep up past it. It got as far as halfway to the next tick. Coolant levels were okay, seemed a little seapage on the rear valve cover but that didn't look like anything to be concerned about.

Going to change from conventional oil to mobil 1, and flush the coolant and throw a new ac delco thermostat in it and cross my fingers. Car is a 07 with 107k miles.

I had one Impala that was a 07 same motor that went all way to the next tick on the temp gauge and I flushed coolant and threw a cheapo dorman thermostat in it and that fixed that one. I am hoping for a sticking thermostat or something.

Also, when I slow down or get into town the temp goes back down. It seems to only keep going up when I am 65+ or so. Ill have to check the fan to make sure its going but I think it is.