Guys,

This is one of those theoretical questions:

I noticed there are a lot of choices for thermostate temp rating.

92' for cold climates, 88' for hotter, but I even saw one rated 86 or something lower (not an OEM installation)

I was thinking, would it be better for the engine to operate at a relatively low temp such as 86'. My logic is lower the temp, less wear on the engine. Less premature combustion (therefore less pinging and knocking)

Because heat softens the metal thus allowing more steel molecules to rub off as the parts turn.

I believe the confusion comes from the fact that European pre 1991 carb engines run with a stock 87 deg thermostat. Only after 1991 you're suppose to up it to 92.

In the volvo Program 87 is very much a standard for NA engines. In fact 92 for 200 is unusual. I noticed in my 1992, the temp was always above mid, checked it all out, even measured the temp and all was fine at 92 deg. Popped in a 87 thermostat and gauge dropped to horizontal. Checked out the temp comp board out - not fitted!

My final conclusion is the instrument cluster is calibrated on the old 87 standard, 92 will give therefor a higher reading.

As per other replies, the hotter the better. Many modern VW's (wife's car) run on 110 high pressure cooling systems. Bad news when you open the coolant reserviour. Factory setting!

REg,

Jorn Oslo Norway

Don't matter where you are, the thermostats are the same on the B230 engines, the normals run a 92, and the turbos run a 87, the turbos need the extra thermal reserve because when you drive them hard they heat up a lot.

The turbo spec thermo is anywhere from 86-88 depending on the brand of thermostat, but the factory original was 87.
--
My 85 760Ti, and her name is Veronica...

In fact, in the pre-computer carburetor days, when an engine started running hot the first thing to do was remove the thermostat. Same combustion dynamics even back then, but we didn't know.

When I took possession of the wifemobile, 1988 244GL with 95K, it consistently ran below normal. The records showed a dealer-done radiator replacement, too.

Even without the BBRD, I knew that normal is normal for an engineered reason. So I had a look, and - voila! - no thermostat at all. Put in the 92C, and picked up 2 mpg the next tank! Now runs at normal.

Good Luck,

Bob

:>)

The hotter the better up to a limit.

"My logic is lower the temp, less wear on the engine."

The opposite is true in a practical sense. When you run cool, you run rich. Gasoline (which, unlike diesel fuel, is a solvent) washes oil off the cylinder walls, increasing wear. And a cool engine is more likely to have the fuel mist condense on the cool cylinder walls than a hot engine.

"Less premature combustion (therefore less pinging and knocking)..."

Maybe, but only when you're in the proper temp zone. Too cool and you'll build up carbon, which can cause preignition.

"Because heat softens the metal thus allowing more steel molecules to rub off..."

Don't worry about that 'til things start glowing cherry red.
--
Don Foster (near Cape Cod, MA)

Nope: stay with the stock thermostat. The hotter the engine, the better the combustion. Your fuel economy will improve and emissions will decline. The only time a lower thermostat is indicated will be for engines producing a lot more heat (turbos) or operating in chronically hot conditions (desert, etc.).

Your stock thermo is 92 C.