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Discussion Starter · #1 ·
First read part 1: http://www.lamborghini-talk.com/vbforum/showthread.php?t=721

Motor Oil 102
Chapter two. It gets more difficult.

We left off discussing that a 0W-30 weight oil is not thinner than a 10W-30 oil. They both have the same thickness at operating temperature. The 0W-30 simply does not get as thick on cooling as the 10W-30. Both are still way to thick to lubricate an engine at startup.

I have heard several people say that Porsche specifically prohibits a 0W-XX engine oil, that it is too thin. Now here is the partial truth I spoke of earlier. We will discuss multi viscosity oils. Earlier we said that a straight 30 weight oil has a thickness of 10 at the normal operating temperature of your engine. The multi viscosity oils 0W-30 and 10W-30 also have a thickness of 10 at 212 F.

The difference is at 75 F, your startup temperature in the morning.


Oil type... Thickness at 75 F...Thickness at 212 F

Straight 30...... 250......................10
10W-30............100......................10
0W-30..............40 .....................10

Straight 10.........30.......................6

Now you can see that the difference between the desired thickness your engine requires ( = 10 ) is closest to the 0W-30 oil at startup. It is still too thick for normal operation. But it does not have far to go before it warms up and thins to the correct viscosity. Remember that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate. Most of the thick oil at startup actually goes through the bypass valve back to the engine oil sump and not into your engine oil ways. This is especially true when you really step on that gas pedal. You really need more lubrication and you actually get less.

Note that a straight 10 weight oil is also too thick for your engine at startup. It has a thickness of 30. Yet at operating temperatures it is too thin having a thickness of 6. It needs to be around 10. The oil companies have added viscosity index improvers or VI to oils to solve this dilemma. They take a mineral based oil and add VI improvers so that it does not thin as as much when it gets hotter. Now instead of only having a thickness of 6 when hot it has a thickness of 10, just as we need.

The penalty is the startup thickness also goes up to 100. This is better than being up at 250 as a straight 30 weight oil though. Oil with a startup thickness of 100 that becomes the appropriate thickness of 10 when fully warmed up is called a 10W-30 weight motor oil. This is NOT as thick as a straight 30 weight oil at startup and it is NOT as thin as a straight 10 weight oil at full operating temperature.

The downside of a mineral based multiviscosity oil is that this VI additive wears out over time and you end up with the original straight 10 weight oil. It will go back to being too thin when hot. It will have a thickness of 6 instead of 10. This may be why Porsche (according to some people) does not want a 0W-30 but rather a 10W-30. If the VI wears out the 0W-30 will ultimately be thinner, a straight 0 weight oil. When the VI is used up in the 10W-30 oil it too is thinner. It goes back to a straight 10 weight oil. They are both still too thick at startup, both of them. The straight 0 weight oil, a 5 weight oil and a 10 weight oil are all too thick at startup.

This is just theory however. With normal oil change intervals the VI improver will not wear out and so the problem does not really exist. In fact, oils do thin a little with use. This is partly from dilution with blow by gasoline and partly from VI improvers being used up. What is more interesting is that with further use motor oils actually thicken and this is much worse than the minimal thinning that may have occurred earlier.

Synthetic oils are a whole different story. There is no VI improver added so there is nothing to wear out. The actual oil molecules never wear out. You could almost use the same oil forever. The problem is that there are other additives and they do get used up. I suppose if there was a good way to keep oil clean you could just add a can of additives every 6 months and just change the filter, never changing the oil.

When the additives wear out in a synthetic oil it still has the same viscosity. It will not thin as a mineral oil. The fear that some say Porsche has that oils thin when the VI runs out is not applicable to these synthetic oils. These oils will always have the correct thickness when hot and will still be too thick at startup as with all oils of all types, regardless of the API / SAE viscosity rating.

Automotive engine manufacturers know these principals of motor oils. They know there is thinning or thickening that will occur. They take these things into account when they write that owners manual. Mineral oil change recommendations will generally include shorter time intervals than those of synthetic oils.

The reality is that motor oils do not need to be changed because they thin with use. It is the eventual thickening that limits the time you may keep oil in your engine. The limit is both time itself (with no motor use) and/or mileage use.

End of part two.

aehaas
 

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Dr Haas: What does the designation 0W/30 or 10W/40 actually mean? These articles are very informative. I am sure this board appreciates the time you are investing in this.
 

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Hi:

You mention that the oil thickens with use after the initial dilution effect. Could you please explain why?

Regards,

Nash
 

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Discussion Starter · #5 · (Edited)
I forget where this quote came form but I like it:

“ON GARAGE QUEENS
I acquired a 71' 429SCJ motor for my current project. The motor had been sitting for 15yrs with all fluids still in it. First thing I did was tear it down completely and what I saw was pretty scary. Rust and sludge was everywhere. Thankfully the owner had enough sense to fill the oil pan with Marvel Myst. to keep it from going to tar. Needless to say it cost me 4k in machining, cleaning and tanking to get her back into shape. The carburetor was not drained of its fuel so its shellacked to the point where I'm not going to re-use it, it can be rebuilt and cleaned but I’m not going for a numbers matching here. So if that’s what happens to the motors I shudder to think of the damage to rest of the car, esp. a F-car.”

That story tells it all. I will explain further.

I believe that cars should be run at least once a month if not once a week. Motor oil thickens just by sitting in your engine. It thickens faster when hot because of accelerated evaporation, oxidation and by picking up dirt and soot in the hot engine. It thickens when cold because of the precipitation of particles, wax formation and the condensation and absorption of water.

I recommend that you do not do the following unless you are a professional capable of working in these environments but...Put some oil in a fry pan and get it hot but not boiling. This cannot be done in your kitchen, it must be a professional environment appropriate for this type of experimentation. The oil will thicken. Put an open cup of motor oil in the freezer (not with food) for a few weeks and keep another cup of the same oil out at room temperature. Warm the cold cup to room temperature. Compare the two cups for viscosity. The cold makes it thicken. The synthetic oils are thought to fair better than the mineral based oils in these situations.

Rust forms when a car sits without oil splashing around inside the engine. Oil picks up water that cannot boil off if there is no hot engine operation and this adds to the rust factor. Even bacteria can grow in oil. It is important to cleanse your engine by running the motor up to full temperature periodically.

In any event, change your oil in the spring of each year at a minimum.




People often ask me what brand of oil is best for their engine. In general, a synthetic is better than a mineral based oil. Yet I use a mineral oil in my Ford Expedition. For this I use the regular Pennzoil Multigrade 5W-20. Make sure whatever you use is API/ SAE SL rated. This is the key.

The “blends” of mineral and synthetic oils may be somewhat better than plain mineral based oils. I think that fully synthetic oils are the best however, particularly for high performance engines.

I believe synthetic oils are all very similar as long as they are SL rated. The main thing to decide upon is what viscosity you need. There is a very wide selection of viscosities to choose from. Each engine and each driving situation for that engine requires a different viscosity range. For that information you need to read all the sections that are coming out in the next few weeks. I personally use Mobil 1 because it is relatively inexpensive and readily available. Currently I am using the 0W-20 in my 575 Ferrari Maranello and 0W-30 in the wife’s Lamborghini Murcielago.

What does the label on the oil can indicate? For the long answer read all my chapters. It is difficult to understand. The short answer is that the first number indicates the severity of thickening that occurs once you turn off your engine and let it cool to room temperature. The second (last) number is how thick the oil is in all engines running under non racetrack conditions. In general, figure out what that second number needs to be for your car. Then pick the lowest available first number, usually 0 (zero).

An oil of the 0W-XX type thickens least after shutting off your engine. It will cause the minimum amount of startup period wear and tear. It will still occur, but less startup wear than with a 5W-XX a 10W-XX or 20W-XX motor oil.
 

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Dr. Haas,

I spoke to George Evans today and he told me there is a new AGIP for the newer Lambos, that the AGIP SINT 2000 that he sends to me is for the older cars, and this new AGIP SINT 2000 GPX is what Lamborghini uses.
Just wondering what your thoughts are on this.
 

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Discussion Starter · #8 ·
If I remember correctly the older Sint 2000 was a synthetic blend and it was only API / SAE SJ rated. I spoke to a chemist there and they told me they were ready to add their newer additives to meet the newer SM rating. The current rating is SL.

This may be their new formulation but I do not see a rating in this information you gave us.

In any event, the newer the oil the better for your engine. Older, worn engines may require thicker oils (or not) but always use the higher rated, thicker oil. There is not a single reason to use an older formulation.

Most people do not get this but this is a fact. Always use the latest oil available. They are better in every single way. There are NO disadvantages in using the newer oil, none. Using the older oils have many disadvantages.

Never-the less, read on and you may (will) learn why. It will be in a later lesson however.

aehaas
 

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Dr Haas: I have a MB S55 and SL600 (2003 & 2004) both with high performance engines. I know you are familiar with the MB FSS maintanence program which does not ascribe to a particular amount of miles or time. I will be averaging only about 3000 miles per year on these cars and use Mobile 1 0W40. Question: Should I still change the oil every 1 year? AS you probably know MB says that you can basicly wait until you reach about 10000 miles before changing the oil. Even when the cars were new they were surprised when I came in at 1000 miles and requested an oil change. They said that I did not have to do it untill 10000 miles. I did anyway on both cars. Do I need to change oil every year with 3000 miles per year on average. I am in florida also. thanks.
 

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Discussion Starter · #10 ·
I will talk about oil intervals later. Just change it every spring for now. Also, the "wrench" will show up on your dashboard just because the time will expire, even though the milage will not.

aehaas
 

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Dr: MB says the "wrench" will show up anywhere from 1.5 to 2 years even if I only drive 3000 miles per year.
On another note, my Owners Manual in the Diablo says that the oil pressure must reach between 5.5 and 6.5 bar when exceeding 2000 RPM (engine at normal running temp). This equates to about 82psi to 97psi. This was written at a time when Lamborghini was recommending (1999) 10W40 or 10W50 Agip Sint 2000. If the gold standard is 10psi for every 1000 RPM why would Lamborghini have this recommended minimum oil pressure in the owners manual? Or is this just saying that, with an engine with a red line of 7500RPM you must have the 5.5 bar minimum from 2000 RPM to 7500RPM?
 

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Discussion Starter · #12 ·
That makes no sense to me. The Murcielago manual says to use 5W-40 for everything except the very hottest conditions, use a 50 weigh oil. I am running a 30 weight now but will try the 0W-20 Mobil 1 soon.

aehaas
 

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aehaas said:
That makes no sense to me. The Murcielago manual says to use 5W-40 for everything except the very hottest conditions, use a 50 weigh oil. I am running a 30 weight now but will try the 0W-20 Mobil 1 soon.

aehaas
Is that a 5 or 10W30 or a straight 30 wt oil you are using in the Murci and is it fully synthetic?
 

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aehaas said:
If I remember correctly the older Sint 2000 was a synthetic blend and it was only API / SAE SJ rated. I spoke to a chemist there and they told me they were ready to add their newer additives to meet the newer SM rating. The current rating is SL.

This may be their new formulation but I do not see a rating in this information you gave us.

In any event, the newer the oil the better for your engine. Older, worn engines may require thicker oils (or not) but always use the higher rated, thicker oil. There is not a single reason to use an older formulation.

Most people do not get this but this is a fact. Always use the latest oil available. They are better in every single way. There are NO disadvantages in using the newer oil, none. Using the older oils have many disadvantages.

Never-the less, read on and you may (will) learn why. It will be in a later lesson however.

aehaas
The newer Agip is a full synthetic and I have been told that the older cars will start to leak if the full syn in used instead of the blend. I will call Evans and find the new rating.
But that would be a disadvantage to a new oil in a older car would it not?
 

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Discussion Starter · #16 ·
Years ago synthetic oils tended to leak with some types of seals. Today that is no longer the case even with those older seals. In fact I was told a newer additive may help seal things up in a leaking system.

I use the Mobil 1 oil, the 0W-20 in my Maranello and the 0W-30 for the first oil change in the Murcielago. I am going to try the 0W-20 next.

aehaas
 

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Discussion Starter · #17 ·
I am borrowing this from another board. I think it is very relavent:



I (me-Dr. Haas) am compelled to comment on the following statements made in the 101 section:
“Pressure and flow are tied together with viscosity, but none have anything to do with lubrication. Lubrication is a property of the fluid, not the force. The oil pump would pump water just as well, but it would offer no real lubrication. If we double the pressure, we double the flow. If you decrease the viscosity to a lighter oil, you increase flow at a loss of pressure. High flow helps to carry away more heat. High pressure helps to keep metal parts like the bearings out of contact with each other (scuffing). High pressure increases flow, as well. Usually in building a street engine for racing, oil galleries are drilled out larger, to carry more oil, and the oil pump is at least doubled in size. I would just guess, that your basic Ferrari is probably flowing in the neighborhood of 2 to 3 or more quarts of oil per second at higher rpm, with over half of it flowing past the crank bearings.”



I give you the following example to help visualize what is really happening. This assumes the oil has no internal resistance. In actuality doubling the pressure will not double the flow but will be slightly less. And thicker oils have more resistance than thinner oils for all situations. But simplified we get the following:

For a 30 wt oil at operating temperature:

RPM....Pressure..Flow
1,000......20 PSI....1
2,000......40 PSI....2
4,000......80 PSI....4
8,000... 160 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 5

For a 30 wt oil at operating temperature
and a higher output oil pump:

RPM....Pressure..Flow
1,000......30 PSI....1.5
2,000......60 PSI....3
4,000....120 PSI....6 The maximum flow because of the oil pop off valve at 90 PSI will be 5
8,000... 240 PSI....12

If we stick with the same weight oil and increase the oil pump output we will increase the pressure and the oil flow too. If we double the oil pump output we will double the pressure and we will double the oil flow.

For a 40 wt oil at operating temperature:
The oil is thicker, has more internal resistance and therefore requires more pressure to get the same flow.

RPM....Pressure..Flow
1,000......30 PSI....1
2,000......60 PSI....2
4,000....120 PSI....4
8,000....240 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 3

For a 40 wt oil at operating temperature
and a higher output oil pump:

RPM....Pressure..Flow
1,000......45 PSI....1.5
2,000......90 PSI....3
4,000....180 PSI....6 The maximum flow because of the oil pop off valve at 90 PSI will be 3
8,000... 360 PSI....12

For a 40 wt oil at operating temperature
with the original pressures

RPM....Pressure..Flow
1,000......20 PSI....0.5
2,000......40 PSI....1
4,000......80 PSI....2 The maximum flow because of the oil pop off valve at 90 PSI will be 3
8,000... 160 PSI....4

Increasing the pressure while using the same oil will increase the oil flow but increasing the pressure by increasing the oil thickness will result in less flow, a lot less. It takes more pressure to move a thicker oil. When you go to a thicker oil the pressure goes up because of the increased resistance, and therefore reduction of flow.

Furthermore pressure does not equal lubrication. Let us look at a single closed “lifetime lubricated” bearing. We could hook up a system to pressurize the bearing. This can actually be done. We could have the oil at ambient pressure. We could then double, triple, quadruple the pressure of the oil. The oil is non-compressible. Regardless of the pressure we would have the exact same lubrication, that of the ambient pressure lubrication.

The physics of lubrication as I said earlier show a 1:1 relationship of flow to separation pressure. Lubrication itself is pressure independent. I will not get into the equations for this board.

Water is a good lubricant. This is partly because of its high surface tension. It is used in many medical devices and other systems that are under or exposed to water. It is just that water rusts metal parts making this unsuitable for automotive engines. It actually has a higher specific heat than oil. It can therefore carry away more heat than oil from bearing surfaces. In this respect water is a better lubricant than oil.

aehaas
 

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>Water is a good lubricant

depending on the materials. In a motor to seperate the moving metal surfaces?...no.

Also, in the category of trivia, there is actually one instance where the old dyno juice is superior to any modern oil. Once upon a time, engines didn't have oil filters. The early non-detergent oils allowed the various particles to settle out and collect where it formed hard sludge-like deposits. Detergent oils keep all that crud recycling thoughout the motor, vastly shortening the service life. So the wise choice is fit an aftermarket filter, or minimally stick with the non-detergent oil.
 
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