Originally Posted by ant
Originally Posted by d00df00d
Originally Posted by ant
Originally Posted by Popsy
You might want to use the LS version for that.
This one has a much higher VI, while still claiming to be unshearable.
Yes it does -- before you add anything to it.
If it were possible to retain that killer VI with an off-the-shelf FM additive, without any downsides, why on earth would Motul not have done that with the LS version?
Motul would have to answer that, but perhaps the cost would be a factor.
Of course. Emphasis on "perhaps," which is the point. Maybe it's something simple, like Motul is cutting corners with their "unshearable" top-of-the-line gear oils. Maybe, as in that's only one of many available guesses. Another is that if you add FM to the non-LS version, you'll just end up with the same specs as the LS version (or worse). We don't know, and probably can't know.
Originally Posted by ant
Do friction modifiers degrade the base oil making it more susceptible to shearing? The LS version also claims to be unshearable.
They apparently increase oxidation rates quite a bit. Not sure if that necessarily translates to shearing but it's clearly undesirable. That's another reason I used the non-LS version. Even though the diff is technically a limited-slip type, it's a type that doesn't need the extra FM, so I figured it'd be better to have the higher VI, better cold performance, and lower oxidation rates.