2004.5 Dodge 5.9 Cummins - Schaeffer 15w40 UOA @ 30,600km

[sonata]

First off, I'm glad this mistake happened. Nothing was harmed and I learned a lot as a result of digging into it.

Here is the first lab result with the mistake

I've been running Schaeffer 15w40 for the summer and this is my third extend drain on it. The last 5 analysis's were on this oil grade(previous was Schaeffer 5w40 and different operating parameters). So I was concerned and not sure what to make of the OXD and COX results in this last UOA to be significantly off trend. What confused me the most was the consistent correlation of OXD and COX in all the past analysis, and the significant change in COX in this analysis. I have a basic understanding off OXD, but up until I looked into it I was ignorant of what COX is. So I started digging.

I called Schaeffer first and asked them what they though of my results. I ended up talking to a competent lady who had operated the lab in schaeffer for 25 years. She was also confused by the sudden change in COX, even though she was not sure what COX was referring to. I did however learn that the condemnation limits for this oil were much higher per Scheaffer then what I had assumed (yes I know engine manufactures have there own limits). She stated Schaeffer wouldn't of flagged this oil unless viscosity @ 100c had reached 18.8 or OXD had reached 35. She explained that in CK-4 oils, OXD was less important.

Next I emailed my Lab, and my rep explained that COX is referring to carbolic acids, and gave me this link for further reading. https://www.machinerylubrication.com/Read/475/oil-breakdown

When asked what could of caused the major spike in COX, she eventually replied back with this:

"I was surprised by the jump in OXD and COX with the similar hours. Upon further investigation, I pulled the hard copy data for your engine and our team had not used the correct IR reference spectrum and I apologize for that. I had them rerun the IR using the Schaeffer 15W40 (2022) IR reference spectrum and the OXD and COX data is more on trend."

This was new to me! I had no idea a VOA of the oil was so important for accurate oxidization readings. Here is my corrected results.

Furthermore she also supplied me with this excellent guide on Oil Analysis - this is chock full of info that I expect pretty much everyone will find useful!

 

[Rob_Roy]

Thanks for sharing what you learned.

Personally I would switch to Schaffer's UOA service. It is very affordable and they know what they are looking for in their own products.

 

[fantastic]

that oil looks stout. You already know this but looks like its thickening with the longer intervals but if the oil company says not to worry until 18.8 then no issues.

 

[sonata]

Thanks for sharing what you learned.

Personally I would switch to Schaffer's UOA service. It is very affordable and they know what they are looking for in their own products.

I'm up in Canada, so sending into the States takes to much time and shipping is prohibitive. The schaeffer tech also stated they don't do oil analysis in house any longer. Maybe they use an external lab for samples sent to them? If your in Canada, I recommend AGAT, comprehensive tests, prices are reasonable and lots of drop off locations so no shipping costs. Regardless, my main take away was that whoever is doing the UOA needs to have the VOA on hand for the FTIR results to be accurate.

that oil looks stout. You already know this but looks like its thickening with the longer intervals but if the oil company says not to worry until 18.8 then no issues.

Yes, I agree. Oil was worked hard as well. Hotshotting travel trailers. So 50% towing, lots of hot weather too. What has been interesting is the amount of make up oil decrease noticeably over this interval. Truck has been fairly consistent at using 1L every 5000km. I'm now at 1L every 6000km-7000km. Truck only really uses oil when towing hard in hilly terrain.