hi guys, just wondering which temperature thermostat would be good to run in a mildly modded c5 a4. i was thinking a 160, any suggestions?

 

the stock one...

 

Not sure where you are located, but a 160 going into the cooler months is a mistake. Your oil temps won't get high enough and the coolant temps will be too low as well. Also, without a fan re-program the thermostat won't do much to keep high temps lower in traffic.

Suggest you heed the advice of the prior post and also do a search on the terms "sweet spot" for further reading before making a decision on what to do with the thermostat.

One other thing worth noting is that the opening temperature of the stock thermostat can be easily modified for less than $1.

 

 

x3

 

160 tstat works great for me.. motorad

 

160* and reprogramming the fans is a decent choice if you're not driving the car in colder temps. I'm fairly certain the first guy who recommended the stock one runs a 160* in the summer months.

 

I do run a 160 in the summer, it takes me 10minutes to swap it out. and reprogram the fans. the trick here is keeping the motor in the sweet spot. IN warm weather there is no fear of running cold coolant or oil temps. I also tune my tires for summer driving and retune for winter.
I've never recommended a 160 stat for anyone who sees 30F temps.

 

how are you seeing "COLD" coolant and oil temps??? the coldest its going to be is 168-170 while cruising.. oil temps are still around 190. People saying oil needs to get above 212 to flash off water vapor is crap, water still evaporates VERY FAST at 180-190. I'm in MD and it gets cold here and I've NEVER had a problem, even with my Fbodys with the same thermostat. I noticed a big difference in power too when the motor would normally be heat soaked hotrodding around town this kept it cool, and detonation free, so your tuner can get even more aggressive with the tuning equaling even more power.

 

PRW performance parts.


5234693 – GM LS Series Water Neck Outlet with Thermostat

GM LS Series Cast Aluminum 90° Water Neck Outlet & Thermostat (GM 5.7L, 6.0L, 6.2L), Polished Finish, Temp 82°C/180°F.


I just installed one of these in my car. It now runs right around 182-185*

 

anyone who thinks oil needs to get to 212F to evaporate has no clue about physics. that myth is just urban legion brought on by those people Im always butting heads with, you know the one who listened to their grandfather.
The oil needs to circulate quickly and lubricate and get to the top of the motor. The sweet spot for an LSX engine is 200F to 210F. And LSX engine likes warm engine temps to achieve proper oil lubricity. its the reason we coded the Oil life monitor with cold start algorithms. Ive only explained this about a thousand times over the last 12 years. Cold engine oil creates too much shear in and LSX engine. Shear will cause thermal breakdown and destroys the engines ability to retain the additive package. Anything below 200F for long periods of time will turn a 200,000 mile motor into a 100,000 mile motor. First thing to go is cam lobes and then lifters. When shear effect the cylinders, you are looking at a 5,000 to 8,000 dollar repair. You brought up tuners. Its there job to give you more HP. they can do this with a colder engine, but what they don't tell you is the if you track your car 5 % of its time and 95 as a cruiser , the cold temps will not give the longevity built into an LSX motor, EVERYTHIN is a trade off. GM is building 200,000 mile motors not 100,000 mile motors . Part of that benchmark is to keep the engine lubricated, Cold oil destroys oil properties. That's why its in the OLM algorithms. We don't make this stuff up. the problem here in this forum is most of the legends in their own mind seem to know more than we do about this car. They quote popular urban legend from the sixties. We did two years of testing on this motor design. Its the first North American motor to benchmark at 200,000 miles. Run this engine cold and it will never see that. AS Ive said thousands of times, this is not your Grandfathers 1955 Buick Roadmaster. So why are people hanging on to those same 60 year old technologies. IN 1955 we were putting a 45 rpm turn table in our cars with a 110V inverter so we could play our own music ( way before an 8 track )and so far from todays technology so why go way back there when thinking motor technology. its changed just as dramatically.

F bodies do not have the same problems a Y body has because of the way the air flows to the radiator. that's why the oil spec for a F is not as critical as a Y body. Shear in a Y ( Corvette ) body is very critical that's why the heat stabilizer is important and critical to the additive package spec for a C5 Corvette

 

Evil, just out of curiosity......Does the lack of ZDPP in current "SN" oils figure into this or not?

 

You have to understand that I retired from GM in 2000 ( it seems like yesterday ) that was almost 14 years ago. Synthetic oils have made significant improvements in the last ten years. The things I talk about and know are from my testing and experiences in the development of this platform. FYI, I can easily remember lots of intimate moments in breakthrough designs from 15/20 years ago, I can remember specific jokes and comments from other engineer. But get this, Last night when trying to fall asleep. ( since my hospital stay and my surgery, I have lots of problems falling asleep ) instead of counting sheep. I tried to put names to faces of fellow engineers I've worked with in the past. I have to tell you it wasn't as easy as I thought it would be. I may be the grandfather people will refer too 20 years from now when people are talking about the 2034 corvette here in the corvette forum. will someone say in 2034, "well that's what ET said "

I am quickly becoming obsolete here.
Bill aka ET

 

I know what you mean. I retired 5 years ago, and now work part time in an auto parts store. Every once in a while, someone from my past will come in the store, and I'll have issues with names....

 

my engine oil temp is 185-200 while crusing with my 160 tstat.. coolant temp @ 172-180 ... coolant temps and oil temps are totally different

 

Same here.

Russ Kemp

 

the question i have which goes along with yours is when did the epa have api sm/sn changed?

i thought it was after the c5 testing was done

we still have api SL in things like the mobil 1 high mileage which has what, around 20% more zddp

 

Lingenfelter specified 160 Tstat, fans on at 180 degrees, and 15w50 Mobil 1 oil in my 98. this car is not driven in the winter however ET's comments on cold oil temps "shear" are interesting. Just my .02...................

 

I have a LOT of Mobil1 in my basement, because Pep Boys had a big sale plus a rebate, at one point in time. I remember the Pep Boys store I bought it at, because it was near where I worked, and it was a bright, sunny day. However, I retired in '08, which means I either bought the oil in late summer of '07, or early spring of '08, as my last day of (full time) work was April 1st of '08.

Having said all that, I just took a look at the oil, and it's marked "SM". So, the change from "SM" to "SN" occurred sometime after '08....