Scotty

Its time to do my fluids...front and rear diffs first. In the owners manual it says synthetic or equivalent...so whats that mean? Can I use non synthetic? Or is there something else? I still intend to use synthetic. However, that statement in the owners manual got me wondering. How many liters does the 11.5 hold? I have been told two different numbers of which are about one liter different. I know to fill to the top hole and a slight bit over but whats the magic number? 4? 5?

Scotty