I thought about this last night as I was giving away my life savings at Tractor supply on Rotella (well not really but you get the idea).
I have a circle of friends that watch out for sales on common items such as oil, filters, tires, windshield wipers and so on. We'll call each other and say "Hey, filters are on sale at NAPA" or "TSC is running a sale on 15W-40". Fuel doesn't really apply since it varies so much accross the country.
If you find a good deal or sale on a product we all use, please let everyone know. I'm all about saving money these days.
And I can tell you..... Rotella is NOT on sale at Tractor Supply right now.