I have an '08, A6 and have been monitoring the temp. It seems to go up to 190 in about 5-10 minutes and go between 190 and 210 depending on outside temp and how hard I am driving. One day it was 97 degrees and the highest it got around town was about 210.
Sounds like your car performs the same as mine.

 

Modern engines need to run hotter. A 160F thermostat is a mistake, unfortunately few understand that and think they are helping their engine - NOT.

Normal coolant temps - 198-220F
Normal oil temp - 210-240F

 

The quoted article aforehand by myself left some of the most important information out. Here is the article in its entirety.

A few of you good folks must have spotted other articles that I have done either in print or online about this subject. At the request of a few folks here I am putting this up for what it's worth and expanding some information about this as well. The argument is about running 160 degree thermostats and the good and/or bad results. Now keep in mind that thermostats have absolutely NO effect on your systems ability to cool, simply a regulator of the range it operates in. So, if you think a 160 will cure an engine running at 220 with a 180 thermostat...forgetaboutit! This is not about cooling capacity at all.

The graph to follow illustrates the importance of how critical optimum coolant temperature is to the longevity and performance your engine. Cooler water makes horsepower and warmer water minimizes engine cylinder and bearing wear...or so it's thought, but only to their own limits and ranges. There is a range where both optimum performance as well as minimal wear share similar characteristics. That number lies in the 175-180 degree range as shown by the overlap in the chart which correspondingly requires a 180 degree thermostat. FWIW, higher operating temperatures of today's engines are to fight combustion by-products and pollution. Also, engine oils are designed to work over a specific temperature range with optimum performance starting at temperatures that require the coolant to be the very same 175ish range. And don't forget the moisture issue. Have you ever seen water vapor coming from your tailpipes? Sure..and the very same thing happens INSIDE your engine. YOur engine forms moisture inside when it cools and condensates on the walls of the inside. This moisture the is washed down into the oil when started and then awaits vaporization by internal temperatures rising enough to bring the moisture to the appropriate corrected vapor point (boiling). If enough moisture is left behind it combines with combustion byproducts to form acids that become dissolved in the oil itself. The oil becomes more acidic as the age of the oil progresses and picks on certain parts eventually. Also moisture will corrode other surfaces. So, it's important to get these engines to a satisfying operating temperature as soon as possible. Usually oil pooling temps are about 30 to 40 degrees higher than the coolant temps. This is a generalised statement and can vary with load and engine design but you can see why you want your oil over 212 degrees to boil out the moiture immediately! A 160 thermostat usually does NOT accomplish this temperature.



Years of research show use of 160 degree thermostats is way too low to be considered for performance or engine longevity. As the chart above illustrates, engine wear increased by DOUBLE at 160, than at 185 degrees. The 160's were invented for and commonly used in older, open loop cooling systems where only 6 pound radiator caps were used, and low 212 degree boiling points were the limit. We know better now.

Many early hot rodders found the 160's to be a smiggin better performing than the 190's, however the in between 180 appears to satisfy both ends of the spectrum. The correct water temperature and thus resulting metal operating temperatures required for the cylinders to achieve a minimum specific temperature in order to allow a fully mixed Air/Fuel charge to combust efficiently is a minimum of 180 degrees coincidentally. If you use 160s be aware that this can have a degrading effect over a time on your engine. I know alot of rodders still using them however to whatever ends they want...and that's okay. Heck, I know guys that run NO thermostat and most of you know that's another book to be covered. I just report what I learn...and you decide what's best for you. I hope this satisfies you information junkies out there.

Steve Jack

 

We have to remember that a "160" thermostat results in a minimum operating temperature of 180, NOT 160. This is because of the unusual design of the LS-series cooling system. On more conventional systems, with the thermostat at the engine coolant outlet, a 160 stat will result in a min operating temp of about 160.
So the article above actually supports the use of a 160 stat in a LS engine.

 

Ah, the voice of reason. Welcome aboard. I've quoted this article a few times.

In the old days ('60s and '70) our performance cars had woefully inadequate cooling systems, and a lower temperature stat actually made a difference. Sometimes I would remove the thermostat entirely. The big block Fords I campaigned with at the strip would bake in the staging area. We ran the heaters at full blast and popped the hoods to try to bleed off heat, sweating like pigs. That isn't the case today. And you're right about optimum operating temperature for performance and longevity. I even had better performance with my hot-running Vorteched LT1 with the stock stat. Of course, temps have to be moderate enough that the knock sensor doesn't pull out timing.

Engines like cool air, but not cool operating temperatures. There's a distinction. I wouldn't go lower than a 180 degree stat in any situation, and the one time I used a 160, I was way down in power and had no heat in the winter. BTW, if you run a 160 degree stat in the winter, you are a fool. Flat out. At least make this a seasonal mod, like snow tires. Or wear an extra sweater.

 

Some of the posters on this Forum like to argue tech statistics when they have no practical background. My 160° T'Stat gave me operating COOLANT temps of 175° to 200°, the OIL temp changes were barely noticeable.

Next we'll have somebody from a Northern State saying that a C6 won't warm up properly with a 160° T'Stat and their heater won't work. Again nothing but theory. Many are garage queens that don't drive their car when it's cold enough to use the heater anyway. My experience in S.Central Texas gave me very few mornings of low 30° temps but the heater worked great within a few minutes of driving, I never had to use maximum heat. Maybe us Southern owners should argue that we use less AC with a 160° T'Stat?

 

For those with 160* thermostats, what are the coolant and oil temps when the ambient temp is 10* and you're driving along at 65 mph? Do you get heat when you turn on the heater?

 

This is true. The design of the system seems to cause the minimum operating temp (which is all a thermostat really controls) to be approx 12 degrees F more that the opening temp of the stat when cruising (I.E. air flow thru the rad is enough that the fan is not needed.)

With my stock 186 stat my min cruise temp is 198, winter and summer with temps into the 90's.

A 160 stat should give a min cruise temp of 172 (this of course assumes the stat actually opens at 160 which is iffy with many aftermarket stats.).

This is too cool for me, engine wise and heater wise. Now I know that a 160 will run much hotter than 172 in traffic but that temp is controlled by fan settings, air flow, ambient temp, rad capacity etc. etc. not the stat. Most of my driving and I would guess a majority of most is at a speed great enough to create air flow, say 30 mph and up that the coolant temp would actually be controlled by the stat. I just don't want to drive around at under 180.

If the 12 degrees theory is accurate which I believe it is then a stat with an opening temp of 170 to 175 would be perfect for me. That would give me a min cruise temp of 182 to 187 degrees.

All of the above theory depends on the stat opening at its rated temp. As testers on this forum have proven lots don't. I would perform a stove top test on any stat before I went to the trouble of installing it.

If you have 160 installed and it cruises in the 180's I think the stat is not really opening at 160. You have an inaccurate stat but it is one I would like to have.

 

We just picked up our new 2008 Coupe (LS3) A6 two weeks ago. With 750 miles on the car, on a day with air temp of 65 degrees on flat road at 65 mph (sixth gear) after 30 minutes of cruising, I got the following readings:

- Coolant Temp - 205 degrees - held pretty constant between 201 and 207
- Oil Temp - 228 degrees
- Oil Pressure - 39 psi
- Trans Temp - 158 degrees
- Battery - 14.3 volts

Looks like my coolant temps are in line with what most other LS3's are seeing under similar conditions...

Any thoughts from folks on the other readings?

 

Those are fine and it seems that you were just cruising. Spirited driving will see higher oil temps (240F+) and transmission coolant temp (215F+) - and those would be fine.

 

Thanks for the feedback adias...you're right, I was just cruising along...your reply is very helpful for a new C6 owner.

 

10* In all recorded history it's never been 10* in Phoenix. We never turn on the heat. We just open the window.

 

Mine hits 219-225F till the first fan kicks on and in stop and go traffic 234 untill the secondary fan comes on. If I'm on the highway around 189-193 I guess this is normal. It seems to me this is a tad bit higher then some of you guys hitting 205-215 on stock settings what gives? Also why do you need a 160 thermo? Can you program the fans to come on sooner with the stock thermostat?

 

Weare talking about C-6's. Only 1 fan with variable duty cycle.

 

It does reach 10* in other parts of the country. The question still stands: "For those with 160* thermostats, what are the coolant and oil temps when the ambient temp is 10* and you're driving along at 65 mph? Do you get heat when you turn on the heater?"

 

I was just kidding of course. The real answer is yes you will get heat from the car heater. It will take longer before the thermostat opens and the coolant starts flowing with the stock stat than with the 160, but more than sufficient heat will be available for the interior so you won't freeze with either stat.

 

Ahhh thanks I didn't notice that, when I did a search I though I put in under the c5 section. I'll go post up there and see what I get.

 

The question still stands: "For those with 160* thermostats, what are the coolant and oil temps when the ambient temp is 10* and you're driving along at 65 mph? Do you get heat when you turn on the heater?"

 

The question still stands: "For those with 160* thermostats, what are the coolant and oil temps when the ambient temp is 10* and you're driving along at 65 mph? Do you get heat when you turn on the heater?"