It's been discontinued for a year and a half. The new high mileage stuff, not called Defy, has the lower ZDDP.
It used to be retail priced in big box stores at about $25 for a five quart jug and $7 per quart container. Someone must have some old stock who thinks it's precious.
Oh, and for the last several years it was produced, only the 10W-40 had the high ZDDP. The lighter grades were rated API SN "Resource Conserving" which limited ZDDP content, which was the reason for it in the first place???
