I've owned my IS250 for over 5 years now. I've covered around 138k miles on it. I dont ever remember seeing the temp gauge going to the half way mark, from what i can remember it would always stay just below the half way mark. about a millimetre below halfway. today, on the way home stuck in some heavy traffic in the extreme heat outside i noticed while glancing at the dash that the temp gauge went to halfway and a mm or so above, it soon came back down to the level just near a mm or so below the half way line. But it did this few millimetre fluctuation from time to time on my journey home. When i got home i checked engine bay, no sign of any coolant leaks or anything. Coolant level is all ok. Just wondering if this is something to be concerned about as I've never seen the temp gauge pass this halfway line before. But then again i dont remember ever driving in this much traffic in this heat.

Thanks

 

Don't worry about it, it was hot out. Well thats my thought anyway.

 

You only need to worry about it if it starts climbing and doesn't stop and doesn't come back down. On a really hot day it will go up more than whatever your average is because even with fans it isn't getting cool air. That is especially true in traffic and sitting with no fresh air coming through the cooling fins.

 

How hot was it outside and you say you were in bumper to bumper traffic? Your electronic fan or the electronics controlling it probably had a hiccup.

Side-note, if you ever see your vehicle starting to overheat...turn on the heat full-blast.

 

Yep, I had to do that with my poor old corolla, I would fear leaving the house anytime it was close to rushhour

But now I have the IS and its not an issue!

 

you should be fine as long as you are keeping good care with everything and all the fluids you should be ok. If its going really high and nothing happend to your car then it could be a faulty temp gauge.