I don't know if there is a shortage, but I did have trouble finding it. Local Austin, TX Costco has it on sale now for $10 gal. in a 3 pack, they didn't have it, but they usually do. Finally found it at the 3rd Walmart for $11.87. They also had 2 synthetic blends and some in a 2.5 gal container. I bought the regular stuff since I wanted to change my hydraulic filters. The photo that does not have a price was $13.47 gal.
My local Wal-Mart only carries the 2 1/2 gallon delo 15 40 now. Had to go to napa for single gal at $16 plus tax here in Tooele. Utah
Ordered 12 gallons from Walmart about $10 a gallon and free delivery.
Ha, Walmart does not always roll prices back, needed another gal. 4 total to replace the oil I removed from the hydraulic reservoir. Price had jumped from $11.87 to $12.97, glad I didn't wait another day to start that job. Bought 3 gal yesterday at the lower price.
Yes, currently the 12 - 1 gal pack is $155.28 or about 12.94 a gallon. I believe it was #128.00 when I bought the 12 pack.
With free delivery it's still cheaper than I can find it locally.