Fresh Oil = Stripped AW ???

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Maybe I am missing something...but it seems that some things are being overlooked. To me there are so many other variables at play during an oil change when compared to the "newness" of the add pack as you are discussing...

When I change the oil...these are SOME of the system changes that may or may not impact the wear metals, and explain why they are higher right after an oil change.

-the system has been opened
-drain plug was removed and re-installed
-fill cap has been removed and re-installed
-new oil has been added to the system with un-known wear metal content
-draining of the old oil has caused an oil flow situation which was not encountered during normal operation which may disrupt settled wear metals in the pan
-during the addition of new oil, oil flow patterns were introduced which were not encountered during normal operation which may disrupt settled wear metals
-oil filter removal (metal wear on threads)
-oil filter installation (metal wear on threads)
-oil filter capability has been reduced (old filters filter better)
-new oil filter has unknown amount of contamination and wear metals
-new oil has unknown amount of contamination leading to increased wear
-during start-up after oil change, there is some period of oil starvation not encountered during normal operation***
-There are even more, but I am out of time...

When the argument is over such tiny levels of PPM, ANY of the above may influence the readings that are being taken. I find it odd that so much time is spent discussing the "freshness" of the add pack contributing to the difference in wear metals when so little control can be had over the experimental system during the oil change.

***my opinion is this is the bulk contributor to the slight spike in wear metals
 
Originally Posted By: edhackett
The "blip" we see in UOAs can not be used to demonstrate this supposed phenomenon either. Carryover is an uncontrolled variable.

Let's take an engine with a 5 qt. sump with 10% carryover that produces a constant 10ppm Fe per 1000 miles, and a 10K OCI as an example. Draw a sample at 1 mile and at every 1K thereafter. This is what the data would look like:

1 mile 11 ppm = 11ppm/mile
1K miles 21 ppm = 0.0210 ppm/mile
2K miles 31 ppm = 0.0155 ppm/mile
3K miles 41ppm = 0.0137 ppm/mile
4K miles 51 ppm = 0.0128 ppm/mile
5K miles 61 ppm = 0.0122 ppm/mile
6K miles 71 ppm = 0.0118 ppm/mile
7K miles 81 ppm = 0.0116 ppm/mile
8K miles 91 ppm = 0.0114 ppm/mile
9K miles 101 ppm = 0.0112 ppm/mile
10K miles 111 ppm = 0.0111 ppm/mile

There you go, the blip seen in UOAs explained by simple math, no extra wear required.

Another thing to take into consideration when viewing the SAE paper is that as a bench test, the fresh oil never sees combustion products. In your car the oil is diluted typically 10-15% with used oil and sees fresh combustion products as soon as you turn the key.

I really wish the authors of the SAE paper had run aged motor oil on a new cam/lifter as a control. All I will say about that paper in general is that if I had submitted that paper to my boss with the rather incomplete methodology section, integrity of the aged oil in question, and figures that did not match the text, my behind wouldn't likely ever grow back.
grin.gif


That said, the paper does provide useful data on the differences in anti wear between new and aged oil, and that 15K oil is still capable of maintaining an effective anti wear layer. The oils themselves were not capable of 15K. All were showing signs of distress (TBN/TAN) at 10K and by 15K one of these 5W20s was a XW-50 and the other two XW-40s, and TAN was 2-3X TBN. Sludge City!

Ed


A very good summary.

Detergents and Dispersants

I still maintain that the results of the SAE Paper is misunderstood by many and the results have been overblown.

I still stand behind my previous theory 2/8/06:

Quote:
MY theory has been that with new oil, the fresh and active detergents starts removing deposits, including metals deposited before the oil change, so the old material is then dispersed into the new oil.

Now as the additives wane from decomposition (detergents and dispersants are reduced in activity/effectivity) through oil aging, the oil has picked up about as much material as it can (loading), oxidizes, and becomes thicker.

So when new oil is introduced, the old crud is whisked up and dispersed into the new oil, which shows higher wear metal content initially, but tapers off as the oil ages.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=21;t=000021

So new oil is always much better than old oil. [Cool]
 
Originally Posted By: MolaKule
Originally Posted By: edhackett
The "blip" we see in UOAs can not be used to demonstrate this supposed phenomenon either. Carryover is an uncontrolled variable.

Let's take an engine with a 5 qt. sump with 10% carryover that produces a constant 10ppm Fe per 1000 miles, and a 10K OCI as an example. Draw a sample at 1 mile and at every 1K thereafter. This is what the data would look like:

1 mile 11 ppm = 11ppm/mile
1K miles 21 ppm = 0.0210 ppm/mile
2K miles 31 ppm = 0.0155 ppm/mile
3K miles 41ppm = 0.0137 ppm/mile
4K miles 51 ppm = 0.0128 ppm/mile
5K miles 61 ppm = 0.0122 ppm/mile
6K miles 71 ppm = 0.0118 ppm/mile
7K miles 81 ppm = 0.0116 ppm/mile
8K miles 91 ppm = 0.0114 ppm/mile
9K miles 101 ppm = 0.0112 ppm/mile
10K miles 111 ppm = 0.0111 ppm/mile

There you go, the blip seen in UOAs explained by simple math, no extra wear required.

Another thing to take into consideration when viewing the SAE paper is that as a bench test, the fresh oil never sees combustion products. In your car the oil is diluted typically 10-15% with used oil and sees fresh combustion products as soon as you turn the key.

I really wish the authors of the SAE paper had run aged motor oil on a new cam/lifter as a control. All I will say about that paper in general is that if I had submitted that paper to my boss with the rather incomplete methodology section, integrity of the aged oil in question, and figures that did not match the text, my behind wouldn't likely ever grow back.
grin.gif


That said, the paper does provide useful data on the differences in anti wear between new and aged oil, and that 15K oil is still capable of maintaining an effective anti wear layer. The oils themselves were not capable of 15K. All were showing signs of distress (TBN/TAN) at 10K and by 15K one of these 5W20s was a XW-50 and the other two XW-40s, and TAN was 2-3X TBN. Sludge City!

Ed


A very good summary.

Detergents and Dispersants

I still maintain that the results of the SAE Paper is misunderstood by many and the results have been overblown.

I still stand behind my previous theory 2/8/06:

Quote:
MY theory has been that with new oil, the fresh and active detergents starts removing deposits, including metals deposited before the oil change, so the old material is then dispersed into the new oil.

Now as the additives wane from decomposition (detergents and dispersants are reduced in activity/effectivity) through oil aging, the oil has picked up about as much material as it can (loading), oxidizes, and becomes thicker.

So when new oil is introduced, the old crud is whisked up and dispersed into the new oil, which shows higher wear metal content initially, but tapers off as the oil ages.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=21;t=000021

So new oil is always much better than old oil. [Cool]




I totally agree with both of you.

Ed- I think 10% oil remaining in the sump is a conservative number. I'm pretty sure you posting this a while back and it made a lot of sense.
 
I also think MolaKule is likely correct. Combine that with the information that Shannow has provided on varnish dissolution and subsequent dropout, it's quite plausible that fresh oil takes up metals in the varnish and "sludge" and if the oil is run long enough, redeposits them back in the formed deposits.

Ed
 
Originally Posted By: edhackett
I also think MolaKule is likely correct. Combine that with the information that Shannow has provided on varnish dissolution and subsequent dropout, it's quite plausible that fresh oil takes up metals in the varnish and "sludge" and if the oil is run long enough, redeposits them back in the formed deposits.

Ed


Yes, all of you have valid points IMO. This is an interesting debate that's for sure.
 
Originally Posted By: edhackett
There you go, the blip seen in UOAs explained by simple math, no extra wear required.

Did the original research do anything to take into account residual contaminants? Or, has anything been done since?

It's all fine and well to talk about requiring time and heat to activate additives, or AW layers being reduced or not replaced at a good rate, but unless we can quantify that, we have a bit of a problem.
 
There was no need to take the residual contaminates into account. They weren't measuring wear in the engine. The cobalt 56 in the lifter used in the bench apparatus was the proxy for wear. Traditional engine wear metals as we know them in UOA were not in the equation at all. The engines were merely a source of used oil.

Ed
 
Originally Posted By: demarpaint
I read here a while back that the fresh oil with the fresh add pack does some cleaning of deposits that accumulated during the prior OCI. That cleaning frees up wear metals that might have been trapped in those deposits. That could be the cause for a slight spike in wear metals early on in the OCI. That also made sense to me.


Agreed. I change on the Hank Hill schedule.
 
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