Regular Thermostat vs. Low Temperature Thermostat?

[orcadigital]

Very true, but as my clutch is working strong, I am a ways from that point as well.

[NOTASIX]

Originally Posted by mikefocke

I hear tell it isn't a simple matter any more of "running up there" as he has a months long waiting list especially during the winter months where folks from up North want to ship their cars to him and get them back for the warmer months.

Make your appointments early....

Good point, Mike
We work from an appointment only basis. Our primary work is M96 engine development and engine production, service and IMSR procedures are done when we have openings.

The fall and winter are our crazy times of year and they fill up fast.

[Wayne 962]

Originally Posted by racer

Another way to consider is the factory could have put any temp thermostat on the car.. They chose the one they did for a reason. I understand we all have access to tons more data than the factory so it would make sense to replace it with one not specified for the car

Charles at LN Engineering ran dyno tests on the car before and after the installation of the lower-temp thermostat, and he found a +5 HP change with the lower thermostat. He believes (and I tend to agree with him), that Porsche set the cars to run hotter so that they could boil water and other contaminants out of the oil in order to provide for longer oil life and less frequent changes (mandated by governments, etc.). I tend to believe that frequent oil changes, and the addition of the low temp thermostat is a positive upgrade for these cars.

Some other things to think about - the 3rd radiator. If you install the 3rd radiator, then the cooling effects won't be fully utilized until the thermostat opens up completely. The stock t-stat with the 3rd radiator will act to artificially inflate the operating temp of the engine because the t-stat will close back up when the coolant is cooled down below the opening point. Also important to consider are the cooling fans. Although the low-temp thermostat opens at 160 or so, the fans won't kick on until the temps get much higher. You can trick the car into putting the fans on earlier, but in most cases that is not necessary.

-Wayne

[Wayne 962]

Originally Posted by orcadigital

Jake Raby is not too far north of me, and I am planning on running up there when my clutch gets low to do the IMS retrofit at the same time. While my Box is an early model, it also has a factory replacement engine, so I am not as worried about it.

You might have the later-style (big external nut) IMS bearing then, which is non-replaceable.

-Wayne

[Timpkin]

Well, after all that great feedback from everyone on the boards, I decided to try the low temp thermostat. My experience thus far is that the temperature gauge simply doesn't peak past the zero in the 180 mark and come back down as it did before. It reaches operating temperature and maintains.

While moving the gauge will reach the 180 tick mark and remain steady. While in traffic it is a little higher between the zero and eight.

Other than that I've noticed no difference from my layman's point of view.

Thank you everyone who chimed in with the advice. I feel very safe with the advice on this forum!

[Wayne 962]

Since the temps of the engine are lower, you want to make sure you increase your oil change frequency. I recommend no greater than 5,000 miles.

-Wayne

[drewbz818]

From what I have read, most oils are thicker when cold an thin out as temp goes up. Thats why in colder climates you use a thinner oil, if not good luck on trying to start your car. If your not tracking your car theres no need for a lower temp thermostat.

[randy_k]

Originally Posted by Wayne at Pelican Parts

Since the temps of the engine are lower, you want to make sure you increase your oil change frequency. I recommend no greater than 5,000 miles.

-Wayne

Wayne, Am I wrong in my belief that the enemy oil is heat? It seems to me, that the warmer/hotter and engine oil gets. It tends to break down faster. If that is true? Then why would it need to be changed more often when the enigne is running cooler?
Just my thoughts.
Randy

[randy_k]

Originally Posted by drewbz818

From what I have read, most oils are thicker when cold an thin out as temp goes up. Thats why in colder climates you use a thinner oil, if not good luck on trying to start your car. If your not tracking your car theres no need for a lower temp thermostat.

Drew, Heat is the enemy of these engines. If that wasn't so. There would be no need for a Boxster S oil cooler. The cooler they run. The longer they live. I have a S cooler here that is going on my none S car. Driving in traffic is harder on these things than about anything. And that's the same as any car on the road. If you're on the track? Air is moving. In traffic. Not so much.
Randy

[turboflyer]

Originally Posted by s_wilwerding

Well, I talked with an automotive expert this evening, and I will admit that I was wrong - he said that an engine will run at about the temperature of the thermostat installed - if you install a lower temp thermostat, the engine will tend to run at a lower temperature.

However, he said that he would not recommend running engines at lower temperatures for a number of reasons. First, he said that modern engines are designed to run around 200 degrees - they are built such that the thermal expansion at that temperature is taken into account. If they run at lower temperature, they run richer, which hurts fuel economy and emissions. Also, he said most modern oils are made to run around 200 degrees - he said that most oils, until they get up to operating temperature, are somewhat thinner - they tend to collect water and gas, which is present until they get burned off at around 200 degrees. He said the major reason that engines have sludge issues is when they are run cooler than what they are designed to.

So, yes, you are correct that your engine runs cooler. However, the downsides are not worth it to me, as I would much rather run it as Porsche designed it and risk the small possibility of heat-related issues, rather than run it cooler, richer, and with the threat of sludging.

+1 A difference of 20 degrees is not going to make a bit of difference to the life and effectiveness of a quality full synthetic oil on the high side. I agree with your mechanic. Especially bad for folks that do short trips and never really get out a run the cars up to temp for long.

[mcmike27]

When I replaced the 90k mile water pump I also installed the 160 deg t-stat along with the Boxster S type oil cooler. All 3 of these items combined have worked very well for me. When we are crusing the temp gauge rarely goes over the white 'tic' before the 180 mark and when in traffic in the summer months the needle is right at 12:00 high and goes back down as soon as the car is back in flowing air. The center rad is on my possible upgrade list but the car has 95k miles and seems to be running fine so I'm inclined to leave it as is.

[drewbz818]

Iii

[drewbz818]

Originally Posted by randy_k

Drew, Heat is the enemy of these engines. If that wasn't so. There would be no need for a Boxster S oil cooler. The cooler they run. The longer they live. I have a S cooler here that is going on my none S car. Driving in traffic is harder on these things than about anything. And that's the same as any car on the road. If you're on the track? Air is moving. In traffic. Not so much.
Randy

That I know, but somebody posted oil is thinner til it gets up to temp, that is not true. It starts off thicker and thins as the engine warms up.

[JFP in PA]

Probably one of the most misunderstood factors about multi-weight oil is do they actually appear thinner when cold then when hot. The short answer (unfortunately) is both yes and no as the result of the convoluted way tech types look at oil.

Straight 5 weight oil will have viscosity values at both low (say 40 degrees C) and high temps (say 100 degrees C). The hot temp viscosity will be lower than the cold temp by a considerable value, depending upon the measurement method applied. Same test on straight 30 weight oil will produce values that are higher at either temperature, a function of the polymer chemistry in the oil molecules. Nothing unexpected here.

Enter VI (viscosity index improvers). When added to the 5 weight oil, you still get the same low temperature viscosity, but when heated, you get the viscosity of the 30 weight oil at that temperature. Cold, the VI package allows the oil to drop to its base or “winter” weight (10 in a 10W-40 oil). As the oil begins to warm, the VI package modifies linkages across the polymer chains, which gives you the higher “hot” apparent viscosities of a heavier weight oil (until the VI package begins to degrade). Technically, it can be argued that “viscosity index” improvements are actually “reductions” in fluid thinning under increasing heat, but to the engine it is the apparent cold viscosity of thinner oil, but the viscosity of higher weight oil when hot.

In absolute terms, viscosity does go down with increasing temperatures; but the engine sees an apparent increase in viscosity (or oil weight) when compared to the colder starting temperature. All a mater of perspective……………

[drewbz818]

I have a 97 986 133k on it, live in southern Cali, what oil would you use? Btw I dont track the car, but is driven daily and does see traffic.

[JFP in PA]

I would stay with a 10W-40 such as Castrol Syntec (ACEA A3, B3, B4 rated) and plan on changing it in the 5-7K (max) mile range. As an adjunct, I would also suggest both the 160 degree stat and the "S" oil cooler, both of which will help to protect both the oil and the engine long term. While other may feel differently, we have been running 160 stats in several cars for a couple of years now, some of which see heavy use, others are garage queens. UoA’s on all of them say the oil is lasting longer, and there are absolutely no signs of increased water or fuel contamination; and no signs of any sludge build ups.

With the 160 stat, the engine is running around the high 170’s to low 180’s (compared to often well over 210 with the OEM stat), more than hot enough to burn off contaminants; the oil is also seeing lower temps as well (limited experience with two cars with oil temp capabilities say 20-25 degrees) which appears to help the oil “stay in grade” longer between changes. Not a bad thing…….

[clickman]

I appreciate JFP's knowledgable contributions to these forums, and am taking his advice on cooling system improvements, as I have followed his oil recommendations. All proven by in-service testing and UOAs.

I have my low-temp thermostat and "S" oil cooler on the way, along with a new water pump. Looking forward to putting them in in the next couple of weeks, and getting my extra 5 HP too!