I just got a nice oil deal for those of us who use 15W-40. I have a 1986 Nissan 720 that seems to be quite happy with that particular weight.
You can get the following Chevron and Mobila oils at Walmart and earn the $7 rebate per gallon.
Chevron Delo 400 SDE SAE 15W-40 (limit two) - Price $13.38 before $7 rebate
Mobil Delvac 1300 Super 15W-40 (limit two) - Price $12.47 before $7 rebate
I ended up getting Two Chevron Delo gallons and Two Mobil Delvac Super 1300 15W-40 for $51.70. Subtract $28 in rebates and the $10 Walmart discount for ordering $50 through Walmart Grocery, and you get 4 gallons of 15W-40 for only $13.70 plus tax.
If you click here
you'll get access to the $10 off $50 discount. There are also other oils on rollback although unfortunately it looks like the Mobil 1 deal has already come and gone.
Hope this helps!