Ok, I just got finished changing out my thermostat in me 3.5l v6. I took out the old 180 degree stat and put in a much cooler 160 degree stat. Now I'm not saying it was easy at all, not by a long shot. The stat comes made at 54mm and the set up for my car is 48 mm. So I had to get it turned down to get it match. The results are awesome so far. After installing the stat and changing the fan settings I went out for a drive. Now remember it was only 50 degrees outside but running on the interstate the car was maintaining around 176 degrees as well around town. Now I haven't data logged a full throttle run yet but I'm quite sure that with the engine running almost 30 degrees cooler I'm hoping to get rid of most of my engine know if not all of it. I will keep y'all posted as to how it performs under long distance driving and fuel economy as well

i've always wondered about stat replacements and making the engine run cooler. isn't that counter to what the engine is supposed to do? i mean, when we start our cars, what do we do? we let them warm up. the engine designers made the engine to perform at a certain temp and if we lower it, won't that make the engine less efficient?

If you put in a 160, why would it be at 176 on the highway ? Sounds like there isn't much difference to the Tstats unless the 180 was running hotter then 180 on the hwy

The 180 ran me 204 on the hwy at 97000 miles and my 160 was running me 176 with a 20 mph head wind with me 65 mph in 50 degree weather. Not sure what it will be in the summer yet but so far she feels real strong all the time now with 0 engine knock now.

Hmm.... what are your fans set too ?


I only ask because on the highway, especially in the winter, the car should be operating right at or much closer to the thermo temp....

As for less efficiency I'll let you know in a few tanks

Cooling fan off
High mph
High 192
Low 183
Med 187
Low mph
High 189
Low 181
Med 186

Cooling fans off
High 190
Low 179
Med 186

According to my predator my temp was 176-178 on the hwy. Unless my temp sensor is going bad

I guess those temps are a little high with a 160 Tstat....


The best way to check and see what the tstat is opening at is to monitor EVIC when you start the car..... once the tstat opens up you should see about a 7-10 degree spike downward in the temp and then it will level off.....


if you are concerned with the operating temps being lower, monitor the temp at which it levels off too and I would most likely set the fan settings @ 10 degrees above the opening

Seems like the car will always be trying to warm itself up and running rich. WOT might have a little more power though. My neon is programmed to think 180 is normal temp since I put a 180 thermostat in it.

what is the norm in that car?

what is the norm in that car?
195 degree.

Intresting.Since i have put on headers highflow cats and duel exhaust my temp under the hood is higher.Will have to think about this mod.Changing it like it has been stated may cause other issues.There is no doubt that our 3.5 run better when its cooler outside.Even running at 200 there abouts is still fine.

Wonder if header wrap would help.

Wonder if header wrap would help.
No thats a nono!it will cause them to rust.I have stainless steel but didn't get ceramic coated.The ceramic really helps keep the heat in the headers and out of the bay.

when i get to put my headers on there gonna be jet hot coated

v666, if you plan on doing this here is the page where i got my fan settings from

http://www.lxforums.com/board/showthread.php?t=230081&page=2

post number 23. its work pretty good for me. when i was fully heat soaked with the 180 stat i would knock like crazy and would have to retard the timing by almost 8 degrees. now i have no knock at that setting. im about to add timing back to see where it knocks at so i can get it set again