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Originally Posted by teleski
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The biggest "trade off" in that article is that it assumes (incorrectly) that the car is going to take longer to warm up leading to additional engine wear, which simply isn't true. Cold starts in a situation where oil takes forever to circulate can result in some level of increased component wear, but the assumption is that the oil is not going to be able to do its job, which would only be the case if high single weight non synthetic oils are involved, or if there were some organic issue with the car's oiling system.
If you step back and think about it, when an engine running 5W-40 oil lights off on a 30F morning, which thermostat is in it is irrelevant as neither would be circulating the coolant at that moment, and the component wear rates are a function of the oil, not the thermostat. As the car with the 160F stat reaches 160F coolant temp, the coolant starts circulation to the heater and the oil cooler, where it warms the oil, helping it to do its job more effectively (take a look at the recent thread about which is more important in an engine, oil temp or coolant temp) . Because the 160F stat is open sooner, the common owner comment is that the car warms up quicker, which is more of a perception that a real fact due to movement of the temp gauge and more cabin heat sooner. In reality, up to the point where the 160F stat opens, both a 160 stat car and a 186 stat car were warming up at the exact same rates, so there is no actual difference in component wear. But because the 160 car is now warming the oil up to operating temperatures, the oil should be circulating more easily and warming up the critical lubricated components.
We have a lot of customers running the 160F stats under all kinds of climatic conditions; I have had the privilege to see the insides of several of these engines and have not seen any evidence of increased wear, sludge build up, high levels of fuel contamination in the oil, or any of the legion of other low temp stat related bugaboos that some people claim result for using them. And as we offer customers UOA's as part of their regular service, I have seen a lot of test results confirming that the oil is happier when the 160F stat is in the engine.
Probably one of the most telling points on the 160F stats is that Porsche uses them as the OEM stat in their max effort engines (Turbo, GT2, GT3). It is also interesting to note that the very late model Boxster and Caymans run a new "thermal management system" in place of a conventional thermostat that keeps the engines cooking at over 225F until you put your foot down, then the system switches to try to quickly lower the coolant to around 185F for as long as you keep your foot in it; then when you lift, the system takes the coolant back up to 225+F. You can read all about this new system in Porsche's own literature on the late model cars.
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