In case anyone is interested, O'Reilly Auto Parts has Castrol Edge on sale until the end of the month. You have to buy 5 qts and you get them at $6.99 each. Zip Code Select | O'Reilly Auto Parts Combine this with a mail-in rebate from Castrol, which gets you $15 back: Castrol EDGE Rebate That comes to $20 for 5 qts. I just did an oil change in late July so it will be awhile before I try this. I've only been using Castrol Syntec so far myself, but I think I may give this a try next oil change.