After reading lots of posts on here, I have narrowed my decision down to four dino oils. They are: Mobil Drive Clean 10W-30 Chevron Supreme 10W-30 Motorcraft 10W-30 Pennzoil 10W-30 Out of the four oils listed, which would be the best choice, and why? The first three listed typically sell for less than $1.20/Quart, and seem to be a good "bang-for-the-buck", based on what I've read here. I've included Pennzoil because lots of people on here have said good things about it. The oil will be used in a 1995 Ford 5.0L Mustang, and a 1999 Grand Am 3.4L. Thanks for the input!