did some research...
http://www.bobistheoilguy.com/aehaas/
taken from Chapter One - Motor Oil 101:
It seems then that we should all be using the thinnest oil money can buy. This is partly true. Let me use my 575 Ferrari Maranello as an example. I drive this car around town. The manual of this car states the target pressure is 75 PSI at 6,000 RPM. The gold standard is that all engines should have a pressure of 10 PSI for every 1,000 RPM of operation, not more, not less. After all, you do need some pressure to move that oil along, but only enough pressure, not more. More pressure is not better, it can only result from the impedance of oil flow. Remember that oil flow is the only thing that does the lubricating.
Note that Ferrari is not saying what thickness of oil to use. That can only be determined by experimentation. My engine oil temperature is running around 185 F as I drive around town on a hot Florida summer day. I have found that the thinnest oil I can buy that is API / SAE certified is Mobil 1's thinnest oil. Even with this oil I get 80 PSI at 2,000 RPM. It is too thick for my application yet it is the thinnest oil money can buy. If I was on a hot Florida track in mid-summer the oil temperature would probably get up to 302 F. I will guess that the pressure would only be 40 PSI at 6,000 RPM. The oil I am using would not meet the requirement of 75 PSI at 6,000 RPM from Ferrari. I would have to choose a thicker oil for this racing situation. The oil I use now would be too thin at that very high temperature. (This is only partly true. Higher RPM running engines use thinner and thinner oils to get more and more flow. I will discuss this later).
High flow does more than lubricate. It is one of the things used to cool the hottest parts of your engine, the pistons, valve areas and bearings. This cooling effect is as important as lubrication in your engine. If your engine is running hot use a thinner oil. The flow will increase and so will the cooling. This is even more important in the racing condition.
Let us go back to the Ferrari manual. My older 550 Maranello only specified 5W-40 Shell Helix Ultra as the oil to use in all conditions. This car was designed for racing. As it turns out Ferrari now recognizes that not every owner races their cars. The newer 575 manual now states to use 0W-40 for around town situations even though Shell does not make this oil in the Helix Ultra formulation at this writing. They also recommend the 5W-40 by Shell if you insist on the Shell product. It is also the recommended oil for most racing conditions.
Ferrari recommends Helix Ultra Racing 10W-60 “for hot climate conditions racing type driving on tracksâ€. Note that they now realize the difference between the daily urban driver like me and the very different racing situation. These are widely different circumstances. I want to emphasize that they only want you to use this oil while racing in “hot climate conditionsâ€. If you are racing in Watkins Glen up north use the 5W-40. If you are racing in Sebring in the middle of the Florida summer use the 10W-60. Around town in any climate, use the 0W-40.
It is time to dispel the notion that 0W-30 oil is too thin when our manual calls for 10W-30. A 0W-30 is always the better choice, always. The 0W-30 is not thinner. It is the same thickness as the 10W-30 at operating temperatures. The difference is when you turn your engine off for the night. Both oils thicken over the evening and night. They both had a thickness, a viscosity of 10 when you got home and turned your engine off. That was the perfect thickness for engine operation.
As cooling occurs and you wake up ready to go back to work the next day the oils have gotten too thick for your engine to lubricate properly. It is 75 F outside this morning. One oil thickened to a viscosity of say 90. The other thickened to a viscosity of 40. Both are too thick in the morning at startup. But 40 is better than 90. Your engine wants the oil to have a thickness of 10 to work properly. You are better off starting with the viscosity of 40 than the honey - like oil with a viscosity of 90.
I repeat: More confusion occurs because people think in terms of the oil thinning when it gets hot. They think this thinning with heat is the problem with motor oil. It would be more correct to think that oil thickens when it cools to room temperature and THIS is the problem. In fact this is the problem.
This is the end of lesson number one.
aehaas
About the author:
Dr. Haas is a physician and surgeon. He graduated from the University of Florida with a degree in biochemistry with honors. He studied motor oils since high school where he did independent studies on this topic. He studied the properties of viscosity.
When he was a general surgery resident in Chapel Hill he studied the flow mechanics of human blood. Today he continues his research by discussion of oil products with chemists in the field and chemists from the oil manufacturers.
He has personal racing experience in Formula Super Vee. He is his own Lamborghini and Ferrari as well as Mercedes mechanic.
