I have seen schaeffers 5w30 provide some great used oil analysis and was thinking about purchasing a case for my 97 cavalier. Would a schaeffers syn blend out preform a full syn? The reason I ask is because the local walmart sells Mobil 1 5w30 for 3.87/quart which is .37 cents more than the schaeffers not including shipping charges I would have to pay for the shaeffers.