While not a place I would think of first, Menards, the Lumber/hardware/home repair people have Marvel Oil. A couple times a year they have the pint sized bottles on sale for $2.50 with a $2 rebate. I think the last rebate was limited to 4. (of course that is four for you and 4 for your friend
). Since I have a home, I will always be able to use the store rebate coupon. I figure I am getting Marvel Oil for $2.00 per quart.
The also stock the # 6012 oil filters. I believe last time I got them they were on sale for $3.
call me cheap, but I actually like the title "thrifty"