So I was on the highway today for about 3 hours. Beautiful day 70F few clouds just a great day to be in the Vette. Checked my operating temps several times. Oil stayed right around 200F. Coolant was rock steady at 180F. Trans was 180-190F. I am really comfortable with these numbers but wonder if the coolant might be a tad low? Heater works great even when it's in the teens outside so I guess its ok. What kind of temps do you experience? Mike

 

Depends on tune and thermostat. See Evil Twin's post below. He's the one who knows best. My stock C5's all ran around 190-200 on the road, higher in traffic.

 

My coolant always sits at 199 once warmed up. Idling in traffic to cruising on freeway.

I have a dewitts radiator w/ oil cooler as well.

 

Too cold. Engine was not designed to run sustained at these temps. Those who think cold is good is living in the 70's.. Oil sweet spot should be 210 F . if the stat is too cold the coolant will be too cold, the aluminum alloy engine is a heat sink. this cold temperature causes shear, making the oil lose it's additive package prematurely. Cold will make more HP, but hot is your friend when it come to engine life, especially with this motor. I wont debate this in open forum... If you notice the red line for coolant is 250/260F.

Bill aka ET

 

You're not having fun until the oil temp hits at least 250.

 

I think that is too cool for best all around performance and combustion. In the old days ( late 60's 70's ) running my big block Camaro it ran best with a 160 stat,(drag raced) So in that time I had a 71 Cutlass Supreme with 350 4 barrel and duel exhaust (factory) and at highway speeds it got around 25 mpg. The first summer I installed a 160 stat and the mileage dropped to 18 mpg, quickly reinstalled the 195 stat. My tuner wanted me to install a 160 stat in my C 5 and I thought it would run too cold so I installed a 180 stat and it runs mostly at 190, I still think that is on the too cool side, but it's a wait and see for me ??? (just one summer with the 180 stat)

 

I am also running a 180 stat, I run 187-193 most times. I'm comfortable with those temps.

 

Seeing as how I want my engine to last another 100K miles I will take E.T.'s advice and increase the temperature my coolant runs at by getting a warmer stat when I change out my Dexcool next month. Thanks E.T.! Mike

 

A stat controls how cold your coolant will get, not how hot. ON a night when ambient is 10*F the only thing that will keep your coolant temp stable is the stat that in the car. if you have a 160F stat, it will keep the car no colder than 160. Its all about heat transfer. when 10*F is running through the cooling vanes of your radiator, it is drawing hot temps and diluting them with cold temps. The stat is a valve that closes when it get to it's set temp. There is a sweet spot for these motors. This sweet spot is designed for efficiency and longevity. Once the engine is at operating temp Oil and coolant should be no colder than the designed temp. The engine is designed to run between the sweet spot and warmer. NOT the sweet spot and colder... Hot is your friend.. tuners will tell you different, but then tuners are paid to giver you HP. not guarantee longevity.. AS I've said here for 15 years... Everything is a trade off. want more HP, run colder, get it tuned, and lose the back end... Longevity. Use regular gas? save a few bucks. Ignore ping, and detonation. allow your car to run at reduced timing, reduced performance, allow internal damage ( pre-ignition )to beat your engine to death.

One of the reason I came here after retiring was to help people get the most out of their Corvette, and to "give back " to a community that supported my Career.

Even after 15 years, I am amazed at some of the advice I see being offered by , bankers, construction workers, shoe salesman, IT guys etc. But worst than that, I see people buying into their advice. I've butted heads with hundreds of these guys over my time here, but it never ceases to amaze me. One of the reason I have said a few hundred times.. " Be careful who your listen to on this forum ".

 

I would like to thank all the responders to this thread. It has been very helpful and educational for me. What I am taking away from this thread is that I should be running a stock temperature thermostat of 187F and see around 200F on the DIC for normal highway operations. I will update when I flush and refill my cooling system and replace my thermostat in the next couple weeks. Mike

 

Just curious why your changing your thermostat?

If you do the flush yourself, or for that matter whoever does it should be aware of the problems associated with air lock in the cooling system and how to bleed it properly... very common problem with overheating after opening up the system...

 

I am pretty sure my Vette has a 160 degree thermostat, since I am more about longevity than performance I will put the stock spec thermostat in while doing the flush/antifreeze change. I have the factory service manual and will follow the recommended procedure to the letter. Thanks for the heads up on "air lock". Mike

 

Living where you do... I would reconsider the stat swap till the ambient temps DROP... ET changes the stat according to the season to keep his car in the sweet spot... your car isn't running to cold.
If it has a 160 stat... however did that probably would have had the fans reprogrammed also...and IF they didn't the stat change wouldn't really do much for changing the OPERATING temps.. just sayin

 

I drove the Vette about 130 miles this morning to breakfast in Mio. Never saw a temp reading above 174F, just to cold, and I highly value E.T.'s advice seeing as how he is one of the guys that brought this great car to us. Come to think of it I have NEVER heard the fans come on ever!! As much as I like working on cars I am getting to old to swap out Tstats every 6 months. Thanks for responding I enjoy everyones input. Now I gotta go wash off all the bug juice before it gets into the clear. Mike

 

yup that is TOOOO cold I would be changing it as well..

 

I was on a 250 mile road trip today. Outside temps in upper 60's. While driving unrestricted by traffic coolant was around 190-200. Then got stuck in traffic. Temp went to around 220 the crept up to 225, then 227 then hit the magic 230. As soon as it hit 230 I am assuming the fans went to high speed. The temp quickly dropped back down to 220 and all was well.

 

That is very helpful information. Did not know this before my trip. I will admit to becoming a tad nervous sitting in traffic watching the temp climb. However i did recall seeing something here about the 235 and the fans going into high gear. Then when the temp hit 235 it started dropping I felt much, much better.

Thank you for this helpful and well described info.

 

ET I have a question for you I found A post from I think 2004 from you with directions how to change your stat which said you did this twice a year. I just installed a 160 stat I also have a mail in pcm tune from ECS my car is not a daily driver only in nice weather hopefully when I can drop the top. was wondering if you still change your stat twice a year and is my set up sound ok.

 

I have not changed my stat in 2 years... I am very sick. Keeping my car in the " sweet spot " was just an optimum easy adjustment. With that switch I also changed my fan settings, one is not good without the other.

Tweaking my car for optimum driving was just something I knew I could do, mkuch like making sure I set my tire pressure " Hot " and not cold.
Because seeting cold in the morning at 30 psi could easily see 36/38 psi in the heat of the afternoon on a HOT 95 + day.

All these things are fine adjustments that when used over a year of driving daily, can make for a better experience.

IN the last two years, I have not put 1000 miles on my car. So I have not changed my stat to the summer stat.

I would "NEVER" leave the summer stat in my car.. Never... and drive it in the winter on a nice crips 15* F day. Hot is safe, and the car can handle HOT.

As Far as your tune goes. If it was tuned with a 160 stat, and with that the fans lowered. You will indeed run into longevity problems... 160 coolant and oil will slowly kill your engine.. but it will not only be faster, so will its demise. EVERYTHING IS A TRADE OFF... Tuners are paid to get you more HP... it feels good... and it looks good on paper., but the Tuner wont buy you a new engine , when ot prematurely breaks.

A well maintained LSX motor can easily see 200K/300K... it was designed to do that.. but it requires that the oil flows freely enough at the right temperature to guarantee lubricity under any conditions.. if the oil is cold for sustained period of time, it is destroying your engine slowly but surely.. Make this a habit and you can easily turn a 300K motor into a 150K motor.

Keeping in the sweet spot is something you can do, but you don't have to do... keeping tires around 30 " HOT " is something you can do.
the difference between running your tires at 30 psi Hot and 36/38 psi hot is about the same trade off.. 30 psi Hot will give you optimum longevity, But allow them to roll at 38 psi Hot when set at 30 psi COLD and the centers will wear out way before the rest of the foot print.. reducing the actual tread life by 30 to 40 %.

I hope I have answered your questions. Don't forget a hot motor will last you a long time, run it cold and it will give you a little more HP. You choose . You cant have both... IF GM wanted more HP they could have used these tricks. Remember I told you that this Motor was the first certified benchmarked 200,000 mile motor ever designed in the world.. It set the New standard for engine longevity.. the previous benchmark design world wide was 100,000 miles.