this doesn't seem right. an oil question
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Joined: Sep 2001
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From: Milwaukee Area
this doesn't seem right. an oil question
Ok, it seems like we have a LOT of different views about oils and their functions.
My name is Ray and I am a senior mechanical engineering student.
I've had my fair share of chemistry classes, but I will be focusing on the mechanical aspects of oil and of course the mechanical properties of your engine since that is my major.
The heat transfer basics:
Oil is not just for lubrication. Oil is the most important thermo transfer substance that your car has. The antifreeze/water mixture you have only gets secondary heat that has to move through the metal engine walls before reaching the liquid. Your oil on the other hand is right there where the heat is being created and therefore has the opportunity to move more heat away at a faster rate. Your oil can get a lot hotter than your coolant does.
Thinner oils will heat up and cool down quicker than thicker oils. However; thinner oils are not able to hold as much energy (heat) as thicker (denser) oils. Also, oils that are to thick or dense will not heat up fast enough (taking heat away from the engine) or cool down fast enough. Thicker oils can also create heat do to friction. You need to have a balanced viscosity.
For our cars anything with a viscosity below 5w may not be holding enough energy for a good heat transfer and anything above 40w may not be soaking up enough heat and anything above 30w may even generate heat.
My name is Ray and I am a senior mechanical engineering student.
I've had my fair share of chemistry classes, but I will be focusing on the mechanical aspects of oil and of course the mechanical properties of your engine since that is my major.
The heat transfer basics:
Oil is not just for lubrication. Oil is the most important thermo transfer substance that your car has. The antifreeze/water mixture you have only gets secondary heat that has to move through the metal engine walls before reaching the liquid. Your oil on the other hand is right there where the heat is being created and therefore has the opportunity to move more heat away at a faster rate. Your oil can get a lot hotter than your coolant does.
Thinner oils will heat up and cool down quicker than thicker oils. However; thinner oils are not able to hold as much energy (heat) as thicker (denser) oils. Also, oils that are to thick or dense will not heat up fast enough (taking heat away from the engine) or cool down fast enough. Thicker oils can also create heat do to friction. You need to have a balanced viscosity.
For our cars anything with a viscosity below 5w may not be holding enough energy for a good heat transfer and anything above 40w may not be soaking up enough heat and anything above 30w may even generate heat.
Joined: Mar 2001
Posts: 37,305
Likes: 18
Students can tend to be a bit "gung ho". He may be right or he may be wrong. Give him a few more years till he graduates and works in the real world before taking him with full validity. In the meantime, we've got Road Rage (that is, when he signs on).
