is your radiator fan working? i guess that wouldn't matter on the interstate so much, but its something simple to check i guess. what mixture of coolant are you using? 50/50? because you could try like 30/80 coolant/water with some redline water wetter and see if it helps any??

 

is the rad in ok condition or are half the fins missing from a 10+year old rad? Sounds like the heat is not being exchanged to air (because it goes down w/ the heat on).

 

has anyone experinced this after installing an intercooler? cause it does block the airflow a little. but it flows through....i don't know.

 

any other thoughts?

 

well i never had any problems but if its only running a little hotter, that could be the case. what size rad do you have on what engine? and what size intercooler?

 

half size single core, D16Z6, and the johnny racer 5"

 

how about using 5W20.......ever heard of adverse effects of using a lighter wieght oil?