I'm looking for reasonably priced 5W50. I can find full synthetic 5W20 and 5W30 for $22 in 5 quart jugs at Walmart which is $4.40 a quart, but they don't sell any 5W50. The cheapest 5W50 I found was Mobil 1 at NAPA for $7. Does it cost more to make the thicker weight oil? Anybody know a cheaper place for 5W50?