Your lab is right, Stuart. To obtain useful information about engine wear, several tests over time are more helpful than a one-time snapshot.
However only one test is all that's needed to measure the ZDDP and acid levels of the oil in use, which is what I'm interested in.
I'm also curious about the diminishing effectiveness of additives over time and how long I can go between oil changes.
If the first test gives good results, I keep using the oil and do another test after a reduced interval from the previous.
Chris
