UOA wear numbers related to sump capacity and engine mass?

[berlyn]

Hello all,

just a question how UOA's should be read.

For example, for an engine holding 5 quarts, Fe ppm let's say is 8ppm. If the engine holded 10 quarts, Fe wear 8ppm should indicate double wear, so shouldn't all values be multiplied by the sump capacity in order to find the mass of the wear metal?

Secondly, shouldn't ideally this value be related to the engine mass? (ok this is not easy to find, somebody should look the engine specs to know that). But isn't it completely different for a 200 lbs engine to have for example 8 ppm Fe wear value instead of a 2000 lbs engine to have the same wear Fe value? (so divided by engine mass)

thank you for clarifying

 

[CR94]

Cylinder swept area (pi×number of cylinders×bore×stroke) of the engine would be easier to determine than mass, and more relevant besides.

 

[berlyn]

well yes, but not for all metals and not for engines with wet clutches.

 

[Linctex]

Yes, there is truth to this.

If I have an engine with a 5 liter sump and then increase it to 10 liters,

should all number now be 50% of what they used to be? Due to dilution?

 

[berlyn]

Hi Linctex

I believe the same probably due to dilution to the double volume for example. But I am not a chemical engineer so I don't now if the relations are linear, non linear, exponential etc. Probably as wear values increase more wear is created due to catalytic reactions or abrasion - closed loop system- but I am not sure.

 

[pbm]

I wouldn't think that the wear numbers would be exactly half if the sump capacity was doubled. Having said that....I would think my Duratech 2.5, with its 5.7 quart sump, could go longer on an OCI than my 2.0 Duratech with a 4.5 qt. capacity being that the engines are very similar (same engine family)....

 

[03cvpi]

The type of engine design will dictate the most common wear metals for that type of engine, mass is not really a factor. Assuming an average 3 ounce oil sample is a good sampling of the oil from a 5 liter sump that ran a fixed amount of miles or hours generated 8ppm fe. If that sump where then increased to 10 liters it would take a longer period of time/miles to reach 8ppm.

It depends on the condition of the engine. I have seen a 2.0 liter engine shedding 60ppm lead in 3000 miles with only 30k miles on it with a 4 quart sump. And a 7.4 liter engine shedding 2ppm lead in 7500 miles with 190k on it and a 6 quart sump.

A good well mixed 3 ounce sample of oil from a vehicle with a 5 quart sump ran 5000 miles is just that, a sample of that oil ran for that long. Every engine is different.

 

[Snagglefoot]

Also, the engine that is geared to run a higher RPM at a given speed should theoretically exhibit higher wear per mile, so sump size and gear ratio both affect the numbers.

 

[demarpaint]

Originally Posted by Snagglefoot
Also, the engine that is geared to run a higher RPM at a given speed should theoretically exhibit higher wear per mile, so sump size and gear ratio both affect the numbers.


Yes, in theory. There are some high revving 4 cylinder engines with small sumps that turn out some impressive UOA reports.

 

[IndyFan]

With Blackstone, does the universal averages column refer to the same engine type or all engines in general? If it is the same engine type, then that would probably be the number for the best comparison, right?

 

[berlyn]

Hello Indyfan,

If it is related to the same engine type it should be the best comparison, as I understand.

So anyone knows the answer of the univ. avg of Blackstone meaning?

 

[03cvpi]

Universal averages are for that particular engine. The only difference might be if the customer omitted information. Example: 2014 Ford 3.5L versus 2014 Ford 3.5L Ecoboost. I would assume the ecoboost may show a little more wear due to the turbo. That could skew the averages if not included in the description. The unit/location averages only apply to your engine.