Why I installed a low temp thermostat.

[JFP in PA]

Originally Posted by pothole

But that's the WHOLE point. The time when you want help with temps is when they are high.

With the standard stat, you are fine in normal driving. Temps are not an issue. What we want is something to prevent temps from getting too hot. Like heavy traffic.

But as soon as the temps start going up, the differences between the two stats fairly rapidly become moot.

So yes, most of the time in normal driving, the low temp stat means lower oil and coolant temps. But to no advantage because the standard car is not running very hot either!

You don't see running coolant (and by default the oil) at 205+F all the time as running overly hot? Again, it is easy to observe the difference in how the oil feels about it as cars running the OEM stat show lower TBN values, and often have their oils "fall out of grade" at much lower mileage intervals than cars running the same oil but a lower temp stat. It is also interesting to note that Porsche's "max effort" cars, the GT2, GT3, and Turbos, all run 160F stats from the factory.

[pothole]

Originally Posted by JFP in PA

You don't see running coolant (and by default the oil) at 205+F all the time as running overly hot? Again, it is easy to observe the difference in how the oil feels about it as cars running the OEM stat show lower TBN values, and often have their oils "fall out of grade" at much lower mileage intervals than cars running the same oil but a lower temp stat. It is also interesting to note that Porsche's "max effort" cars, the GT2, GT3, and Turbos, all run 160F stats from the factory.

I'm metric when it comes to oil and coolant temp. My car runs at 88 or 89C steady state. That's totally fine.

What I don't like is how hot it can get when stressed or in traffic.

Moreover, the thing the low temp stat is advertised as being preventative for is bore scoring on some of the larger M97 engines, which is supposedly a problem related to very high temps and hot spots.

But I am at a loss as to how it does this since at higher temps, there's no difference between the two stats.

GT2/GT3/Turbo all have very different engines (well, did until the Mezger was dropped fairly reently). There are lots of things they have that may or may not be a good idea for the M96/7 engines.

[JFP in PA]

Originally Posted by pothole

Moreover, the thing the low temp stat is advertised as being preventative for is bore scoring on some of the larger M97 engines, which is supposedly a problem related to very high temps and hot spots.

But I am at a loss as to how it does this since at higher temps, there's no difference between the two stats.

Easy, when the coolant in an M96/97 is running 210F (99C in your world), a commonly observed steady state driving temp when measured with accurate instrumentation (which the dash display is notoriously not); due to the rather intricate cooling system layout in these engine cases and cylinder heads, there are areas of the engine that are often 20 to 30 degrees F warmer than the observed coolant temp due to restricted coolant flow. This leads to prolonged alloy component distortion and is one of the principal reasons these engines are prone to both cylinder head cracking and cylinder wall problems. Throw in faster oil degradation and you have a potential issue..........

[pothole]

Originally Posted by JFP in PA

Easy, when the coolant in an M96/97 is running 210F (99C in your world), a commonly observed steady state driving temp when measured with accurate instrumentation (which the dash display is notoriously not); due to the rather intricate cooling system layout in these engine cases and cylinder heads, there are areas of the engine that are often 20 to 30 degrees F warmer than the observed coolant temp due to restricted coolant flow. This leads to prolonged alloy component distortion and is one of the principal reasons these engines are prone to both cylinder head cracking and cylinder wall problems.

I read my temps from the AC panel hack, not the temp gauge. It's not quite as accurate as direct from OBD, but I doubt it's anything like 10 degrees out (which is a lot in C). I have connected via OBD once and there was only a couple of degrees difference.

I do not think these cars run at 99C in normal driving. The stat would be wide open and the engine would then cool down. In steady state driving with good air flow, the stat is going to be partially open, not wide open.

Like I said, mine runs at 88 to 89 when cruising, which makes perfect sense given the stat starts opening at 86.

[JFP in PA]

Originally Posted by pothole

I read my temps from the AC panel hack, not the temp gauge. It's not quite as accurate as direct from OBD, but I doubt it's anything like 10 degrees out (which is a lot in C). I have connected via OBD once and there was only a couple of degrees difference.

I do not think these cars run at 99C in normal driving. The stat would be wide open and the engine would then cool down. In steady state driving with good air flow, the stat is going to be partially open, not wide open.

Like I said, mine runs at 88 to 89 when cruising, which makes perfect sense given the stat starts opening at 86.

I am not a fan of the AC display hack and many of them are not accurate either. We prefer either actual quality instruments (after market gauges) or the use of the PIWIS or Durametric system, both of which have proven to better agree with aftermarket instrumentation setups.

We have clocked literally dozens of customer cars running well north of 205 F, even in relatively cool ambient air temperatures. Problem is that the OEM stat starts to open at 186F, but does not fully open until much higher temps are reached. You can verify this for your self by suspending an OEM stat in a beaker of water and monitoring when it starts to open, and when it is fully open.