GM expanding dexos D approved oils

[Mossyoakglock]

I'm still learning all this oil stuff but are you saying that you need at least two, maybe three, UOAs on a specific oil to confirm if it is really working?

For example, you go from AC Delco 0W-20 to M1 ESP 0W-30 and you get the same iron numbers on the first UOA. But, on your second UOA with ESP, if your iron numbers drop, that's a better indication that the ESP is doing it's job?

Would it be the same the other way around in that you could go from M1 back to the Delco and you iron numbers stay the same. But on your second UOA on the Delco oil, you iron numbers could, in theory, jump back up?

 

[kschachn]

I'm still learning all this oil stuff but are you saying that you need at least two, maybe three, UOAs on a specific oil to confirm if it is really working?

For example, you go from AC Delco 0W-20 to M1 ESP 0W-30 and you get the same iron numbers on the first UOA. But, on your second UOA with ESP, if your iron numbers drop, that's a better indication that the ESP is doing it's job?

Would it be the same the other way around in that you could go from M1 back to the Delco and you iron numbers stay the same. But on your second UOA on the Delco oil, you iron numbers could, in theory, jump back up?

Who is saying that? It would take a statistically significant number of samples. There is no standardized test that uses random spectrographic analyses to make comparative quality determinations between oils, so neither the test methodology nor the analysis has been worked out and available.

Also note that Blackstone has said that they have observed no significant difference between any oil they have tested. So two or three is not even in the ballpark.

The problem is the large set of uncontrolled variables in this kind of test. You don’t necessarily (and usually do not) tease a minor variable out of the noise just by increasing the sample size. Wear differences between two fully formulated motor oils is not a major variable.