I have used the "conventional" and maxlife flavors, and would not have a problem using "full synthetic" however it is physically impossible that thats what it is. Think about it, lube shops don't seperate used oil according to conventional, syn blend, and syn, and neither does anybody else that recycles oil for that matter. Therefore, the base stock they make starts out with a little bit of everything in it before they re-refine it. Their "full synthetic" may be "more synthetic" than the others, but any oil that is any part re-refined is syn blend at best. You can't take a mix of all oils and come up with a "fully synthetic" base stock, its just not possible.