Quaker State and Pennzoil? Same company, same bottles, difference prices. But, what, if any, differences exist in the oils? I was at Walmart last night and saw the 5 quart jugs of Quaker State Peak performance for $9.27, which makes it the cheapest 5 quart jug of oil you can get at Walmart. The Pennzoil is down from $13.50 to $12.00, but is it really worth the extra $2.73 to get the Pennzoil?