Right now at Walmart you can score some STP for FREE or very close to it with the $1.00 off one STP product coupon. Check out the deal plans below:

Buy STP Gas Treatment $1.97
Use $1.00 off one STP product
= $0.97!

Look for the yellow rebate on these bottles (as in picture above) and if you find them, this will be a money maker!

Buy 1 STP Gas Treatment $1.97 each
Use $1.00 off one STP product
Submit for the rebate on the product
= FREE + make $1.00!