My local walmart is having a sale on the Mobil 1, when do Walmarts usually have them on sale? Just once a year? I paid $18.88/jug (5 qt jugs), which comes to $1 off the normal price for each quart, not bad but its a PITA cause my 5.4 takes 6 quarts while the 4.6 takes 5 quarts. I'm using Supertech oil filters which I think can last 5k miles tops whereas the M1 on a conservative estimate could last 8000-9000 miles w/ normal duty driving (non-severe according to Ford). If this is correct, then I'd have to buy another quart at regular price to top it off after the filter change.