[Greimann]

The oil is a little closer to the "action" than the water is. It is in direct contact with pistons, valves, and and such. Some of the oil temperature is due to engine combustion heat and some of it is due to frictional heating as it is being sheared between moving parts. That and oil, because it is more viscous than water, will be slower to give up it's heat in a radiator that is smaler than the one for the water. So oil is going to a bit warmer than the water, especially when the car is driven hard. A freeway cruise on a cold day will bring the two pretty much equal because the cooling systems of both will be operating optimally, pretty much at their thermostat temperature.



Which leads to my trivia question: Why is the term "radiator" a misnomer?

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[Brian]

thanks for the answer. that makes sense.

my touareg has both an oil temp and water temp gauge. sometimes, like you said, the two temps are very similar, and sometimes not.



i'll take a shot at the trivia question...

radiator is a misnomer because technically a radiator is something that gives off heat, normally for the purpose of heating a space.

in a car, you are actually using a 'radiator' as a cooling device. more of a 'dissipator' than a 'radiator'. still gives off heat, but not for the purpose of heating. more giving up heat to get rid of it in the hopes that the fluid inside will cool down.

i also normally think of a radiator as being a stationary, static device. in a car, it's a very dynamic system. more convection than radiation, but in reverse



is that close enough? do i win a free greimann instrument panel???? <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[Greimann]

[quote name='Brian' date='Nov 9 2005, 08:38 AM']..

i'll take a shot at the trivia question...

radiator is a misnomer because technically a radiator is something that gives off heat, normally for the purpose of heating a space.

....



is that close enough?  do i win a free greimann instrument panel????  <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

[right][post="12218"]<{POST_SNAPBACK}>[/post][/right][/quote]

buzzzzz - The judges say no <img src="/forum/images/smilies/968/sad.gif" class="smilie" alt="" />



Heat can flow one of three ways, Radiation, conduction and convection. A car's radiator actually exchanges heat by conduction, not radiation (like the sun) so technically it is a heat conductor.



Just one of those things that just got started and we stick with it for old time sake.

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[Brian]

it was shortly after my thermodynamics classes in college that i decided to not be a mechanical engineer!!!!

never understood all that heat transfer stuff.

it was worth a shot!

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