Originally Posted By: d00df00d
edhackett -- forgot to thank you for chiming in. Always appreciate input from a real expert.
This post suggests that the term "hydrotreated" could also be used for Group III components. Is that wrong?
Yes, hydrotreated could include what might be Group III. The definitions for the two oils in the MSDS are fairly vague. The CAS for the primary component does not specify mild or heavy hydrotreating. The minor oil component lists synonyms for both mild and heavy hydrotreated oils.
On further thought, the categories I listed in my first post probably should be thought of more of guidelines rather than gospel. It It seems that it is a convention for "severe" hydrotreating to be used for describing Group III like Mobils' Visom and the like. I've become used to seeing that description for known Group III base stocks, and "hydrotreated" for CAS numbers for known group II oils. Motul may have chosen to use a more generic CAS for their MSDS to obscure their formula or the actual oils may be heavily hydrotreated "generic" Group III. They'll likely not tell.
There's a lot of leeway allowed in MSDS. That's one of the pitfalls of trying to divine an oils formulation from the MSDS. For the purposes of the MSDS, any number of CAS numbers could be used. From a purely practical safety standpoint, it really doesn't matter if the CAS points to Group I, II, III, IV, or likely most Group V oils. They are all close enough from a firefighting, toxicity, exposure, protective equipment, or treatment standpoint, to be treated the same. Some companies fudge more than others.
It will be interesting what they have to say.
Ed