How to GET a deal on near'bout anything (as my Grandma would have said)

Bo relized that it is near'bout time to change the oil the the cars. (He has always done this, we have never HAD it done) The last time he changed it we had a coupon from Advanced Auto Parts and it worked out after coupons and buying when on sale, BOTH vehicles (his truck, and my van) was $19.88 total.
Well, he asked me where is the deal at for oil this time.....I don't know why he thinks I would know this information right off the top of my head!!??
Anyway, the next day (I kid you not) in the mail we get an ad from O'Reily Auto Parts! What is on sale CASTROL OIL (the only kind we use), so I started looking for some form of coupons, wether store coupons or Castrol coupons....NOTHING.
But I did see a REBATE on the Castrol website for up to $20.00 back, but then I noticed it is for when you get your oil changed at QUICK LUBE! Now that's not going to work!
Well ya'll know me enough by now that I am not going to stop there! I emailed Castrol and told them how we always change our own oil, Bo only uses their oil, and the rebate would not help in our situation.......did they have any coupons they could mail us? 2 hours later I checked our email and Castrol had emailed me back saying "WE WOULD LOVE to send you some coupons, tell us for what products and we will get them out to you!"
I emailed them back told them what types of oil and 30 min. later I recieved another email telling me my coupons were going to be mailed , we would get them in 7 to 10 days!
Now we allot $10.00 a month for car needs such as this, so this will not come out of our grocery budget, or effect our PORCH project. In fact setting aside a little along has helped when I needed a tail lightbulb replaced, Bo needed some antifreeze that type thing....NOW REALLY BIG MATTERS ARE A DIFFERENT STORY, and you are probably thinkning something like this is no big deal......but when you count every penny to be spent.......it is a big deal.... and we NEVER NEVER EVER NEVER put ANYTHING on credit cards not even an oil change! If we can't pay for it now, what makes us think we could pay for it next month or the next?
I am telling ya'll this so you can see how to LOOK FOR A DEAL on near'bout anything, anything you need
If you can save where ever you can, save! That is money we can put toward something else that we need.