What is the normal operating temp for 03 IS 300? My gauge never goes above halfway but after driving if I pop the hood, it will burn your hand. The engine bay is very hot even with ambient temps outside in the 80's currently. Is this normal because it seems like wires and plastics could warp or melt at a certain point?

 

I'm not sure the normal operating temp, but my gauge also reads half way. That's normal operation. Keep in mind that the engine has a steel block, high compression, the engine bay is small and its all well insulated. Nothing to worry about.

 

Oh and yes, the plastics (mainly connectors) take a real beating from this heat. So if you plan on disconnecting anything electrical, be VERY gentle or they will crack. Most connectors can be purchased on Ebay. Lexus will make you purchase the entire harness. The wires/insulation seem pretty stout and I've never had any issues involving heat with them.