2006 Tahoe Cooling system running to cool. 5.3L Flex

[Noggles]

Not a bad point about the engine wearing slowly or not as properly, however. In my case, I can easily get it up to temp sitting idling in traffic or in the garage where there is minimal airflow, even when the fans kick on the coolant temp rises to 200ish. It just takes a little longer to climb and has a faster recovery.

Of course another good point might be winter weather but I don't have to worry about that in Fl and mostly did the lower thermostat to keep a little more heat away from the AC condenser when its 110* out.

Something to consider is oil temp. If your oil isn't getting to the proper temp (or fast enough), condensation isn't evaporating out. Higher engine temps (to a point) will prolong engine and oil life. I just did a nerdy dive into coolant temps a few nights ago and the engineers on the LS1 program found that peak power and efficiency was made around 210-220 degree coolant temp. They found that less than that and the block actually robs some of the heat generated from the combustion process to heat up the block first. I have a 160 thermostat in my trans am and like your truck it runs around 170-180 unless its really hot outside. After reading what I did I think I am going to put a stock thermostat back in and retune the fans. I think this might be costing me a couple mpg compared to what it was getting before the cooling system rebuild and cooler thermostat.

 

[Dantheman1540]

Something to consider is oil temp. If your oil isn't getting to the proper temp (or fast enough), condensation isn't evaporating out. Higher engine temps (to a point) will prolong engine and oil life. I just did a nerdy dive into coolant temps a few nights ago and the engineers on the LS1 program found that peak power and efficiency was made around 210-220 degree coolant temp. They found that less than that and the block actually robs some of the heat generated from the combustion process to heat up the block first. I have a 160 thermostat in my trans am and like your truck it runs around 170-180 unless its really hot outside. After reading what I did I think I am going to put a stock thermostat back in and retune the fans. I think this might be costing me a couple mpg compared to what it was getting before the cooling system rebuild and cooler thermostat.

Oil temp is definitely something to consider but I don't believe it's a cause for concern at least from my experiences. When I changed from the factory thermostat to the 160 I noticed no loss or gain in MPG nor do I see any excessive moisture in the oil during changes. Something that may aid this is the fact the truck seems to heat up after the initial shut down. For example, I will drive to the gas station during which the temp gauge hung around the 160-170 mark. Upon starting the truck bak up after parking shutting the engine off and fueling for 5-10 minutes the temp gauge will be higher up sometimes at or even above the halfway mark. Of course, as soon as the coolant starts flowing it cools off quickly but that's just another time which the oil will heat soak and get up to temp.

 

[Noggles]

Oil temp is definitely something to consider but I don't believe it's a cause for concern at least from my experiences. When I changed from the factory thermostat to the 160 I noticed no loss or gain in MPG nor do I see any excessive moisture in the oil during changes. Something that may aid this is the fact the truck seems to heat up after the initial shut down. For example, I will drive to the gas station during which the temp gauge hung around the 160-170 mark. Upon starting the truck bak up after parking shutting the engine off and fueling for 5-10 minutes the temp gauge will be higher up sometimes at or even above the halfway mark. Of course, as soon as the coolant starts flowing it cools off quickly but that's just another time which the oil will heat soak and get up to temp.

I think I dropped about 2mpg since the cooler thermostat in my trans am and really dont notice any performance difference. Curious what will happen when I go warmer and see if the mileage picks back up or not

 

[Dantheman1540]

I think I dropped about 2mpg since the cooler thermostat in my trans am and really dont notice any performance difference. Curious what will happen when I go warmer and see if the mileage picks back up or not

I'd be very interested if it does go back up! Those cars seem to be capable of very good highway mpg if the setup is right.