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Motor Oil - All Chapters, Inclusive -Hat Tip to Ferrarichat.com

58K views 41 replies 27 participants last post by  dtdillon92 
#1 ·
This cleared up alot of questions and misconceptions I had about oil. I think many of you will find this interesting. I posted this here out of fear that the post would be lost some day and I would be unable to access it. Enjoy.

Here is the link to the original post on Ferrarichat.com

Posted by username 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.



Chapter One - Motor Oil 101

I think it is time to go over passenger car automotive engine oils in detail. I will be writing several articles to be published soon so I will try to get some of it out here. I feel this is a very general topic for all car owners on this board.

This is a very difficult topic to comprehend. Everybody including good mechanics think they are experts in this field but few understand engine oils. Most of what I hear is the opposite of the truth. It is however easy to see how people get mixed up as there is always some truth to the misconception.

Please forgive me if I am too wordy or even verbose at times. I will be redundant for certain. This will be in areas that people have to hear things over and over again to get it right. Some will never be able to understand these concepts unfortunately. I base my thoughts on those whom I have been listening to in various automotive chat rooms and discussion with mechanics. I will try to minimize technical terms and be somewhat vague rather than exact. I will round and average numbers to make the point simple rather than mathematically exact. Thickness has the same meaning as viscosity. Viscosity is a measure of the resistance of a fluid (liquid or gas) to flow. Fluids with high viscosity, such as molasses, flow more slowly than those with low viscosity, such as water. Again, I am trying to explain general principals as I know them.

The greatest confusion is because of the way motor oils are labeled. It is an old system and is confusing to many people. I know the person is confused when they say that a 0W-30 oil is too thin for their engine because the old manual says to use 10W-30. This is wrong.

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. It is said that 90 percent of engine wear occurs at startup. If we are interested in engine longevity then we should concentrate our attention at reducing engine wear at startup.

Oils are chosen by the manufacturer to give the right thickness at the normal operating temperature of the engine. I will say this average oil temperature is 212 F, the boiling point of water. On the track that temperature is up to 302F. It is important to realize that these are two different operating environments and require different oils.

I will discuss driving around town first. Everything I say will be based on these conditions. At a later time I will discuss track conditions. Everything I say will be as accurate as possible without looking everything up and footnoting. I am trying to be general not ultra specific.

One thing that is no longer important is the ambient temperature. Older automotive owner manuals often recommended one oil for the summer and another for the winter. This is still necessary for air cooled engines but is no longer a consideration in pressurized water cooled engines. These engine blocks are kept at around 212 F all year round. The oil is around the same temperature as well. This allows for a single weight oil all year round. Again, this is not the same as on the track where the coolant temperature is slightly higher and the oil temperature is much higher.

Please forget those numbers on the oil can. They really should be letters as AW-M, BW-N or CW-P. The fact that we are dealing with a system of numbers on the can makes people think that they represent the viscosity of the oil inside the can. The problem is that the viscosity of oil varies with its temperature. A “30” weight oil has a viscosity of 3 at 302 F ( 150 C ) and thickens to 10 at 212 F ( 100 C ). It further thickens to a viscosity of 100 at 104 F ( 40 C ) and is too thick to measure at the freezing point of 32 F ( 0 C ).



30 weight oil:

Temperature ( F )....Thickness

302...........................3
212..........................10
104..........................100
32..........................250 (rough estimate)

The automotive designers usually call for their engines to run at 212 F oil and water temperature with an oil thickness of 10. This is the viscosity of the oil, not the weight as labeled on the oil can. I want to stay away from those numbers as they are confusing. We are talking about oil thickness, not oil can labeling. This will be discussed later. Forget the numbers on that oil can for now. We are only discussing the thickness of the oil that the engine requires during normal operating conditions.

The engine is designed to run at 212 F at all external temperatures from Alaska to Florida. You can get in your car in Florida in September and drive zig-zag to Alaska arriving in November. The best thing for your engine would be that it was never turned off, you simply kept driving day and night. The oil thickness would be uniform, it would always be 10. In a perfect world the oil thickness would be 10 at all times and all temperatures.

If the thickness of oil was 10 when you got in your car in the morning and 10 while driving it would be perfect. You would not have to warm up your engine. You could just get in the car and step on the gas. There would be little wear and tear on you engine, almost none. Unfortunately the world is not perfect.

The night before when you drove home from work the car was up the the correct operating temperature and the oil was the correct thickness, 10. Over night the engine cooled to room temperature and the oil thickened. It is 75 F in the morning now (I do live in Florida). The oil thickness is now around 150. It is too thick to lubricate an engine designed to run with an oil having a thickness of 10.

It is time to introduce the concept of lubrication. Most believe that pressure = lubrication. This is false. Flow = lubrication. If pressure was the thing that somehow lubricated your engine then we would all be using 90 weight oil. Lubrication is used to separate moving parts, to keep them from touching. There is a one to one relationship between flow and separation. If you double the flow you will double the separation pressure in a bearing. The pressure at the bearing entrance is irrelevant.

In fact the relationship between pressure and flow is in opposition. If you change your oil to a thicker formula the pressure will go up. It goes up because the resistance to flow is greater and in fact the flow must go down in order for the pressure to go up. They are inversely related. Conversely if you choose a thinner oil then the pressure will go down. This can only occur if the flow has increased.

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 tracks”. 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 conditions”. 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

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#29 ·
Great write up, for the people that actually spend the time to read through the whole thing, it will provide them the information they need to make an educated decision on what oil they should be running. I think this weekend I am going to change my DD civic oil to 0-30, I think that i am going to leave the STI at 5-30 for now but in both of them they are going to stay Synthetic for obvious reasons in the article.

This was great to send to my buddy who has a 70 challenger who thinks that he need to put in 10-40 or thicker plus a **** load of oil stabilizer, then wonders why the car is running hot...
 
#33 ·
Excellent but heres a question.

"previously" before i read this i was lead to believe that the cooler the oil the better and i have fitted a greddy oil cooler on top where the Top mounted standard intercooler was (now have FMIC)

I dont track the car and im pushing 400+ WHP which gets used fully once or twice a day

Is this a good idea to use a oil cooler for daily use.?

"have i missed the point.?" it is 1am and a few beers later.!
 
#34 ·
Also ,

im 3,000km into a new built cosworth block and running mineral "from Subaru" and have changed twice now.once at 1,600km as recommended by Cosworth and again at 2,400km because i wanted to. Ive read in other parts of IWSTI that you should only change to synthetic after around 15,000km but after reading this thread im not so sure and i think it would be better to change right now to fully synthetic.

Any comments.?
 
#36 ·
I read all the chapters but I'm not sure how to determine if my 2005 STI in Arizona is @ 10PSI per 1000rpm. All I know is my tuner recommended Shell Rotella 15w 40 due to the hot weather here. But according to this write up, 15w anything is bad due to how thick it is at startup vs other thinner oils. On top of that, Rotella is not synthetic. The previous owner of my car used Amsoil 10w40 in Florida, but Amsoil 0w40 seems to be a better choice. Man my head hurts now... I hear Subarus love Rotella, but i'm not sure where that all started. I know alot of people run it and have very little oil consumption (something that wasn't really covered in this write up). Regardless, I think I'm going back to Amsoil synthetic on my next oil change. I'll even give the 0w30 a shot in this 115 degree summer Arizona heat. I agree with the logic that oil at startup should be as light as possible but still optimum at roughly 212 degrees F. Interesting write up for sure. Now to test some oils.
 
#37 · (Edited)
I read all the chapters but I'm not sure how to determine if my 2005 STI in Arizona is @ 10PSI per 1000rpm. All I know is my tuner recommended Shell Rotella 15w 40 due to the hot weather here. But according to this write up, 15w anything is bad due to how thick it is at startup vs other thinner oils. On top of that, Rotella is not synthetic. The previous owner of my car used Amsoil 10w40 in Florida, but Amsoil 0w40 seems to be a better choice. Man my head hurts now... I hear Subarus love Rotella, but i'm not sure where that all started. I know alot of people run it and have very little oil consumption (something that wasn't really covered in this write up). Regardless, I think I'm going back to Amsoil synthetic on my next oil change. I'll even give the 0w30 a shot in this 115 degree summer Arizona heat. I agree with the logic that oil at startup should be as light as possible but still optimum at roughly 212 degrees F. Interesting write up for sure. Now to test some oils.
Unfortunately, that article has some issues so I would not even think too much about that information. Read the comments here with input from engineers and a tribologist. Dr Haas' Motor Oil University Article.

A 15W must pass the cold weather cranking test at -20C and a 10W must pass it at -25C.
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I would say the main problem with Rotella 15W40 is that it's not a "synthetic" oil, although it's probably an ok choice if you plan to change your oil every 2,500 -3,000 miles max. Amsoil 10W-40 would be a better choice as it is a very stable oil (less viscosity modifiers than a 0W). Not sure which Amsoil 10W40 you are referring to, but Amsoil XL 10W40 is very slightly thicker than Amsoil AMO 10W40 at operating temp. The XL 10W40 is closer in viscosity when hot to the Rotella 15W40 than the AMO is, although AMO is made from better base stocks and I believe it has more ZDDP.

The only 30 grade Amsoil that I would run in that car is Amsoil HDD 5W30. And that's only if I confirmed that the oil pressure was good during the entire interval. HDD makes Rotella T6 5W40 look light (in additives, but not viscosity). Again, don't stress about the cold cranking viscosity unless you plan on driving your car to Saskatchewan. ;)

Rotella T6 5W40 gained popularity among many enthusiasts over the past few years because it is a mixed fleet gas/diesel oil that meets API SM specs for gas engines, has a decent amount of ZDDP, and is easy to find. Another good 40 grade oil that I would consider in AZ that's easier to find than Amsoil is Mobil1 10W40 High Mileage.

-Dennis
 
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