Mineral or Synthetic oil- how can you tell the difference?
Q: We buy mineral and synthetic gear oil, same viscosity grade, from the same supplier. My mechanic is concerned that we are mixing up the oils, as the oil seems to have a different odor as we use How can we tell what’s what?
A: Perform regular quality checks on your incoming new oils, and obviously on your in service equipment. We recommend running a FTIR (Fourier Transform Infra Red Spectroscopy) to evaluate the unique lubricant molecular fingerprint. (See figure 1) This is a very useful tool employed by us in conjunction with other tests to determine unknowns or comparisons. One would deduce that the unknown sample is a mineral base. Regarding the odor- some formulations do have a much more pungent odor than others due to required additive packages, however this is not a reliable indicator of product since this odor changes once the lubricant is placed in service. Smart application of this technology can avoid lubricant mix ups. It is particularly cost effective when synthetic product is 4 to 20 times more expensive than mineral oil.
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Figure 1 - Comparison of IR spectra of unknown (blue) synthetic gear oil (gray) and mineral oil (red) The unknown appears to be a mineral oil based on analysis of specific peaks (or lack thereof) |
-Marc Jean
