L_popo

2005 Z51 auto car, so obviously it has an oil/trans cooler. 126K miles, trans/coolant haven't been flushed since about 50K

Could this be contributing to my hot temperatures cruising at 70mph up I-35E on a 100 degree day, no spirited driving, no traffic, just steady movement at 70. A/C on the whole time, stays cool without an issue.
Temps are as follows
Coolant: 225
Transmission: 225
Oil: 241, 26 PSI @ idle (normal and not worrisome, I know)

What should I check for other than swapping out coolant and trans fluid in my future.

hotrod_tim

I personally went with a Dewitts radiator when my original went out and a 165F thermostat in my 07. I noticed a big drop in temps im also at an elevation of 5280 and its pushing 100 today with no problem

FatsWaller

Check that the lower half of the AC condenser that sits in front of the rad isn't obstructed by bugs, dirt, plastic bags, etc. Same for the rad. Those areas should be checked and cleaned yearly if required.

NYC6

Watch that trans temp, it’s high especially for cruising at speed, I found out the hard way and recently had a total rebuild due to overheating. Along with the circle D rebuild I also did a Dewitt’s rad with EOC/TOC, B&M cooler for trans behind passenger side fog light and tonight I’m wrapping the trans lines way too close to the headers and cat.
Took it for a test drive earlier today and logged data, , it was 92* here in NY today and cruising about 65mph for about 20miles. Oil-217*, Coolant-212*, trans-165-167*.
In traffic with little airflow and heat from headers trans temps go up to 190-200 and higher if I got stuck for longer and I wasn’t taking a chance going much higher in this 90* weather, insulation hopefully helps lower that number.
You’re in Texas, I would move up to a Dewitt’s or similar radiator at the very least. I would then see if the improved rad lowers trans temps and if not add a cooler. Your coolant and oil isn’t dangerously high but your trans temps very well might be.

Jstan2014

OP’s ....Temps are as follows
Coolant: 225
Transmission: 225
Oil: 241, 26 PSI @ idle (normal and not worrisome, I know)


2012 Grand Sport A6. I was out on the Texas 13O toll today cruising about 25 miles one way at 85 mph. The outside temp was near 100 degrees.
Coolant temp 195
Tranny temp 203
Oil temp 231
As mentioned above, maybe there’s a little dirt and/or debris obstructing the radiator. I’d definitely service the radiator.

FAUEE

Start off with new coolant. Your old coolant is the blood of the system, and old coolant isnt as effectove.

I would also consider of the coolant sensor is reading the correct temperature. Check for obstructions on the radiator, like plastic shopping bags or similar.

ssg10587

What Fauee said, replace your coolant. It's an easy and cheap job and will usually help then go from there.

dr_gallup

No doubt replace the coolant, it's only good for 5 years if you are using the factory fill Dexcool. But I doubt that will make any difference. Far more likely the rad is partially blocked as that is a well documented problem with the C6 and that needs to be dealt with or at least eliminated as a cause. Since the coolant is what keeps the trans and oil cool, if you can get the radiator to work better then the other temps will come down too. Doubt it's a sensor since all temps are somewhat elevated.

L_popo

Thanks to everyone for their responses and feedback comparasions.

Gonna see if the radiator/additional coolers have crud in them and get the fluids changed to make the difference.