MB parts number 000-989-28-03 diff oil
Something with good water resistance is good. Many people like to use a light colored product so that, if it seeps out dark or black, they know that the boot around the inner CV joint has been compromised. The CV joint grease inside the boot is black.
Some folks will use a CV joint grease. That way, if the CV joint is compromised (and this is a very common occurrence), it will be CV joint grease on the outside of the boot to mix with the CV joint inside the boot; and keep the CV joints well lubricated.
Hope that helps.



