Question about 3MP's study

[cheetahdriver]

3mp,

would like to see terry express some values for the ending protocol. i like the 100ppm iron value as an end point, not sure about the other metals. agree that the vis is not likely to be the cause of the final drain, nor would i guess is TBN.

i guess since the oil isn't all going out the tailpipe, i will have to retract the oilburning part of the "oilburning GM tolerance monster".

still is the best test i've seen. keep up the good work.

[ July 19, 2003, 10:37 PM: Message edited by: cheetahdriver ]

 

[3 Mad Ponchos]

quote:

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would like to see terry express some values for the ending protocol. i like the 100ppm iron value as an end point, not sure about the other metals.

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Actually I would tend to think the warning sign is the rate of wear rather than the raw numbers... if the increase in particulates became more pronounced between samples, that would be a greater concern than just a total value.

Cheers, 3MP

 

[Drstressor]

3MP- You are correct in a general sense. When the slope of the metal accumulation curves starts to increase, you will know that you have gone too far. But wouldn't an accelerated wear trend carry over into the next oil test? I mean, if you wait until you actually cause some damage, you will likely have started a different wear pattern that could affect your later results.

The total value of accumulated wear metals (iron in particular) will affects both the amount of available detergent/dispersant and the anti-oxidant capacity of the oil. Once you accumulate >100 ppm Fe, you additive package can go down hill fast. That's why they use 100 ppm Fe as a safe cutoff point.

If the point of the study is to answer the question: "How long can Brand X oil hold up before going out of spec?", then you are doing a valid study. On the other hand, if the question is: "How long can Brand X hold up before engine damage occurs/", you will need to use a different engine for each oil. I think you are using the appropriate end points to answer the first question.