explanation of oil additives

[will123123]

Analysis of an new oil sample used in a high performance gearbox application highlighted the following main elements: -

silicon 1200ppm
sodium 15ppm
Boron 62ppm
Moly 970ppm

Obviously these are due to the additives in the oil, could anyone work out the likely additives being used in this oil from this admittedly very basic information and the reasons for their presence (ie anti-foaming or anti-friction purposes).

Thank you in advance for your assistance.

 

[drwebb]

Si is unusual at over 25 times higher than expected from anti-foam. Sure that isn't Sulfur (S)? One explanation may be leaching from formagasket-type sealants, but it's a pretty high number and could affect foaming performance (too much silicone oil can increase instead of decrease foam). Sodium at that level may be a trace of sulfonate for corrosion inhibitor. Boron is likely a dispersant component for cleanliness, but also adds some anti-oxidancy. Molybdenum is probably a thiocarbamate for anti-friction and anti-wear. Another clue would be what application is this gear oil for? Automotive gear oils for differentials are put together different than those for manual transmissions, and both are different from industrial apps. Are Ca, Zn, and P all non-detect?

 

[ivymike]

I looked at the Si number and thought "what did they do, scoop this sample off of a beach?" The OP describes it as a sample of new oil, which I took to mean that it has not been poured into the engine yet.

..then I noticed it's for a gearbox, not an engine, and decided I didn't know much about that topic.

 

[will123123]

I confirm that these figures are from unused oil taken straight from the bottle. Tests have been carried out more than once and the results are always similar. The person who carried out the analysis did highlight his surprise at the high silicon level.

The application is a race car gearbox and the grade has a particularly low viscosity to reduce efficiency losses.

 

[25362]

Siloxanes have been known to have high spreading (wetting) rates on metal surfaces even when exhibiting high viscosity.