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Q & A: air cooling of oil

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Most recent answer: 05/29/2010
Q:
Hello, Im sure to you folks this may be a simple answer to the question I propose. I have come across an interesting forum that many people in the Air Cooled Volkswagen community use for parts, info, etc. A curious arguement has arised. Being that most Electrical oil coolers equipped with fans turn on thermostatically @ 180 degrees, why is that well below the temperature that water boils ( 212 F)? The main reason we want the engine to reach operating temperature is for it to allow water to evaporate out of the oil. So my question exists as: does oil pressure( in the engine) coupled with operating oil temperature effect evaporative actions of the water to occur at an earlier temperature? For example, on my car the hottest operating temperature I run at is 190 degrees. The average oil pressure I operate at is 20 psi. Please forward your response to #### As you can see I show great interest in quelling the confusion scientifically. Thanks-Jon
- Jon (age 32)
Waipahu, Hawaii
A:
You don't have to actually boil water to get it to evaporate quickly.

I'll guess that a temperature below the boiling point of water may be used because the chemical degradation of the oil goes much faster at higher temperatures.

As for the advantage of running at standard operating temperature, I always thought that was largely because at lower temperature the oil is too viscous. Of course, one could use thinner oil, but then it would get too runny at the operating temperature. Lowering the operating temperature is impractical because it would take too much cooling apparatus to keep the engine cooler on long runs.

Mike W.

(published on 05/29/2010)

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