about $600 a quart? To be specific ...a GM instructor showed me a 2008 differential that had the CV clutches inside that they are having trouble with...the fluid he said is made with $600 a quart Sperm Whale Oil, what the heck??? Why would GM do that when there are other, cheaper, better solutions?? please somebody answer this and hope fully either tell me the truth, or proove me and vthe instructor wrong!!Thankyou