# PPM Equals How Much Wear in mm?

#### AEHaas

What If : Tested engine : 6 cylinder engine holding 4 quarts of oil (no make-up) and having 20 k on the car and 10 k on this oil had on analysis: 20 lead 20 iron 20 chromium 20 tin 20 copper 20 aluminum If the oil was replaced after each 10 k interval to 100 k total car miles what would be the theoretical wear in mm of the engine bearings. Say each analysis of 10 k miles gave the same results. Say there were 4 total, all the same size. I know there is lacking information but still, what are we looking at in real wear possibilities. Does this give us a range? Is it just nanometers - in which case who cares? What are your thoughts of wear numbers to real, measurable wear after 100 k mile on the car having consistently elevated numbers as above. aehaas

#### 427Z06

That's kinda' like asking, if someone has a cholesterol level of 7.8mmol/l, how thick will the build up of plaque be in the walls of their arteries. Way to many unconstrained variables to arrive at a meaningful answer. You'd at least have to constrain it to a particular engine design where the metallurgical makeup of the wearing components and the associated wear rates are known. You may also have to take in account parts that just chemically contribute to the UOA through corrosion like the bronze screens used in VTEC systems.

#### srivett

It would be interesting to see how many million parts the total amount of oil added up to. Then you could come up with the total # of parts of metal that came out the drain plug. Doing some math would then lead you to how many grams of metal came out. How much does the average CC of metal weigh? It would be over 1 gram because metal sinks in water. I would figure it out myself but I can't stand chemistry. Steve

#### Gary Allan

The thing you can't integrate out of a ppm is if the metal ejecta is evenly distributed, localized (like the thrust side of rod journals), or scattered randomly from impurities/imperfections in the material that's (as 1struck termed it - I think appropriately) chemically leaching. The only thing that we have (and our oil analysis pros) is statistical data bases that show what is normal ..and what is not. I agree that it would be too engine/sump specific to project a given wear marker to actual measured wear. In familar terms ...you can only treat it symptomatically and don't know the impact ..only that the symptoms are to be minimized whenever possible.