Oil Samples
When storing a sample, you may see changes in the re-test if the sample is not air tight. Volatile things like fuel dilution may be affected. There was a lot of talk about the certification of these labs and what metrics they established in a previous thread.
In order for the results to mean anything, the normal acceptable range for what they find needs to be established. Ford has already stated that fuel dilution should be less than 7% (if memory serves me), but I have not heard from them what they consider to be normal for the wear metals. And with the engine block made of a compressed alloy, our results may look different than other diesel engines.
The main thing I always look for in my airplane engine is a trend. Is a certain metal increasing or decreasing and why? That is the prime indicator to a potential component failure.
Hope this helps.
On the testing issue, occasional duplicate testing may not be a bad idea from a reliability check. Keep in mind the methodology of testing for certain elements can be different, hence normal ranges will not necessarily compare for specific tests. So for example method for Copper versus another could have range in parts per million of 5 - 200 as normal, the other method, 20 - 230. If your reading is 5 and 19 respectively, they are basically the same result, one method maybe a better one for testing at the lower levels.
Given the limited data, on the 6.7, I would think that the trends are most important for sure. I Would sure like to see the results. It will be interesting to se fuel dilution has gone down, how your oil holds up with this longer OCI.
Thanks for the info. It doesn't sound like it would hold too much merit to saving samples if they will "go bad" too easy. The original results in that case would hold more merit than would re-testing.
I just want my records to be as good as I can get them. Although, when I bought my oil the lady at Walmart rang me up for 2 jugs and not 3. The price difference was cool, it just shows I got 10qts and not 15 (I know the engine only takes 13).










