I've been using this oil in several older vehicles/ farm tractors in the summer especially since it's about $2 per gallon cheaper than the name brand HDEO's. I figure it will hold up better than a PCMO in the hot summer heat and keep the engines cleaner too. But lately I have not seen any of this oil in the WM's here. I was able to get it in qts and gallons up until a couple months ago. Anyone notice the same thing, or know the reason for this?