The use of hot or cold plug will not really affect the engine operating temperature.
A hot plug is used for cars usually driven at slow speeds, and in a lot of stop and go situations, like in city traffic. The plug tip will stay hotter than a cold plug, keeping the tip from fouling at idle or low engine speeds.
A cold plug is used when higher speed driving is the norm, like cruising around on roads with little to no stop and go traffic. The colder tip will prevent pre-ignition (knocking).
The impression I get, from reading the posts on this site, is that the 3077 does a pretty darn good job overall on these 4 bangers.
I also agree with what bobc4 said in the post on overheating:
Stick with it having it running and on the road is fantastic and worth the frustration.
Happy Motoring,
Dan
