Quote:
Originally Posted by Dannys M3
I don't believe you can correlate ppm to miles driven. Wear rates have not been established. With the majority changing at earlier intervals my concentration can only be compared to others also running 15000 intervals. When I did spectrometric oil analysis for the Air Force it was easy to tell when a jet engine had its oil changed. All concentrations would drop and then rise very quickly beyond the limits set for certain alloys. The trend analysis we performed was about sharp increases in alloy concentrations. I don't think people realize how little parts per millionth is.
There are also other variables. Did everyone drive more than 20 mins before taking their samples? Or did they just start the engine and warm it up. I was running 80-90 mph on the highway for at least 30 mins on my hour drive home prior to taking my sample and boy was that bitch hot.
I wonder what the variance in readings are between calibration samples and the different machines Blackstone has. Has anyone questioned what their actual calibration procedure is? I'm sure its in Blackstones interest to have everyone test their samples as often as possible.
Just my .02
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I'm not sure that you can either but if you say that a 5K and 15K intervals are not comparable and imply that with more miles on the oil the ppm of lead will increase, then dividing the ppm by miles driven would be a better measure than just looking at the lead levels alone.