And there it is! Thank you very much for the information.

Though I must also ask, not having done this before, how difficult is the installation?
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EASY! Since you have a '97 you should be able to swap the knock module on the side of your PCM with the new one so you shouldn't need a CASE learn.

can we clarify something here: why dont you want to do a 180* t-stat?

I totally missed that reaming and sludge comment. Thanks Toasty!

Yes, let'* discuss that more. Considering the vast majority of this Forum runs them with no issues, and some of us are drilled? I'm running a drilled 180 myself, but that'* a little different setup to support it.

Great, thanks! I did a test checkout, and it apears I can get what I want for about $170 before shipping. I may be doing this soon, and it'* a great thing that I won't have to do a CASE learn because the shops that can do that around here are few and far between.

Well, with a 180° thermostat the wear factor would be nearly twice, worse fuel economy, oil sludging, etc. Not to mention that my car isn't programmed to run with a 180°, so it would be nothing but harmful.

Basically, the pistons and the rings expand at different rates than the cylinder walls do. GM found the optimal temperature range to keep things in close tolerance and proper running order. With the stock 195° the clearances are optimal for compression with a minimum of friction. If they went to all the trouble of finding the best range for wear vs. performance, why deviate?
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Wear factor worse? Please explain. I've never heard of that.

Worse fuel economy? Myth. I don't know of anyone that saw a decrease, and we're running HUNDREDS of these on this Forum. Have been for over 5 years now.

Oil sludging? Never heard of that either.

Many cars here that are not 'programmed' for it run them fine. But your INTENSE PCM will be programmed for it. That'* really moot though. It makes no difference. A 160° thermostat may be a different story.

I'd like to know where your information came from. Our experience over 5 years and hundreds (if not thousands) of cars, and thousands more on ClubGP dicatate quite the opposite of what you posted.

i, too would like to see some supporting arguments and sources fo rthe information provided. I have had nothing but great results with my 180* for 3yrs/40k miles as have thousands of other people as stated above by bill

A quote that helped drive my decision:

You also can't deny that engine wear increases as operating temperature decreases. Granted, it'* far more dramatic below 180 but it'* still greater at 180 than at 195.

Think of this also, running a lower temp thermostat without a PCM reprogram is really not a good idea. Coolant temperatures will vary from a range of 180 to 220 degrees (or whichever activation point it is) until the radiator fans engage, rather than the narrower band with the stock thermostat. Is that higher range of expansion and contraction really beneficial to the engine? Especially considering that the materials inside expand and contract at different rates?

The pistons in our 3800'* are aluminum correct? And the block itself is cast iron? These metals expand and contract at different rates according to their temperature. GM designers found that the best thermostat setting to keep tolerances optimal for compressioon and minimal wear was 195 degrees. Again, why change?

As far as oil sludging, the reason is simple. With a higher operating temperature, the engine warms up more and burns off condensation more quickly. The result is less oil sludging.

It'* also fairly understandable why fuel economy will be decreased...a cooler engine runs richer. Heck, you can smell the unburnt fuel coming out of a cold engine that'* just been started. The difference between a 195 and a 180 would be VERY minimal, but still present.

Running a 180 thermostat is not going to kill your car, if I gave that impression it wasn't my intention. It is however, pointless unless you have sufficient engine modifications to require a lower operating temperature. Even the increased wear and sludging AREN'T going to make the engine die young, but it would wear out sooner than an engine that'* been run with a 195 it'* entire life.
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By design, the rings are the 'flexible' interface between the cylinder wall and the piston itself for thermal expansion coefficient differences between the two components. This is designed into the engine by GM and every other manufacturer.

Nobody here has any sludging, nobody here has any fuel mileage problems, and nobody here has ever had any other adverse effects.

For you, the 180 is more important from a reliability standpoint, as the L36 MIGHT live a little longer with a cooler running engine when you consider the EGR stovepipe area and a cooler intake passage nearby.

Friction and combustion are the causes of heat in an engine. As heat increases, oil viscosity decreases. Your wear theory is backwards in that sense.

Your theories are interesting to chew on, but not backed up in practical experience.

Again, the differences between the 180 and the 195 that would cause wear, sludging, and poorer fuel economy are minimal enough to go unnoticed, but still present.

In any event, agree to disagree.

Speaking of my plenum, it'* been almost five years since it'* been replaced. How long do those things last, usually? I don't want to let it get to the point of hydrolocking the engine.

I understand that the L67 does not experience such difficulties, further reason for me to get the swap. I've also heard of people doing a "top end" swap...how difficult would this be if say, the UIM failed and the upper part of the engine was off anyway? Would it be just a direct fit or would other modifications need to be done? There would probably be a necessity for a PCM change and of course the drivebelt configuration. Fuel pump and injectors maybe? Just a thought, it would be easier than a full engine swap.
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