Delvac 1 - ester content and IR oxidation??

[Extreme-Duty]

Hello,

it has been pointed out here many times but has never been backed up by "hard data". Sometimes it might be said because people simply expect D1 to have a good dose of ester. But, isn't it all wild speculation? For now, I have to believe that D1 contains/contained between 0.4 and 25 or so % percent ester as an additive or base stock. The very low number of 0.4 is from Widman's post refering to SAE Paper 2001-01-1968. Widman - base oil groups

The agenda of this SAE Paper was to say that a Gr. II based 15w40 is on par with a syn. 5w-40 HDEO, so the composition (or their analyzing accuracy) might not have been important to them. Also, why should XOM complain about any misleading information on the proprietary composition of it's products? The synthetic 5w-40 mentioned in this document is likely to be Delvac 1 API CH-4. 0.4 % ester could very well refer to the ester of ZDDP. However, D1 has been reformulated twice (at least) since CH-4.

In general, Delvac 1 used oil analysis show relatively low FT-IR oxidation readings. Is this because of the absence of esters or is it because most labs report the "oxidation increase" over the virgin oil IR-Spectrum/baseline? Can anyone show me a Delvac 1 or D1 ESP VOA including IR-test?

I tend to believe that all molecules with an oxygen bond will show up at the same wavenumber. Is that simply wrong?

Please do not turn this into another base stock discussion, I just want to know what we get with the products we pay for.

 

[JHZR2]

As I recall, bonded oxygen occurs at various wavenumbers, depending upon what it is bonded to. The double-bond oxygen is in a range of 1500-1800 wavenumbers (cm^-1) and the single-bond oxygen that is part of the ester functional group is a bit lower, 1000-1200 wavenumber, IIRC.

I suppose you need both to accurately fingerprint an ester vice some other organic species.

There are lots of other Oxygen containing functional organic groups, each with their own wavenumber range fingerprint. Not all oxygen bonds, or even single or double bonded oxygen show up at the same point in the FTIR scan.

 

[Tom NJ]

Synthetic ester base oils (diesters and POEs) absorb most strongly at the carbonyl (C=O) area of 5.8 microns (~1700 wavenumber).

For FT-IR oxidation readings to be meaningful they must subtract out the virgin oil absorbtion, thereby removing any interference from ester base oils or additives. Unless the used oil analysis states that it has subtracted out the VOA of the exact same formulation, I would tend to disregard the data. I would consider oil thickening, insolubles, and TAN to be better but not perfect indicators of oxidation. That said, I would consider TBN, metals, and contaminations more important in determining oil condition than oxidation.

There are oils with tiny doses of esters. Sometimes these are potent esters designed to balance seals. In some cases I believe they contain a token dose just so that the ester remains a formal part of the formulation.

Tom NJ

 

[Extreme-Duty]

Sorry, I'm a little late with this. Thanks for your help. That's probably the information I needed.