I got a posi today, went around gettin all the seals, C locks, and gaskets and everythign but i didn't get any oil. the GM posi lube stuff is a lot bit pricy from what i have heard so I'm looking for somethign else, possible something better. What do you guys use? I've hard the synthetics don't need a posi additive, do they? whats the best stuff to get? its a stock GM posi...