I want to let you know that, so far, I am very pleased with Wal Mart's Super-Tech 10-30 synthetic oil and their Champion Labs oil filter in my 1993 Mercury Cougar 5.0 V8 with 38,000 miles. The engine seems to run smoother and this is backed up by close to a 5% increase in fuel mileage.(I have a digital dash).
I saw a guy who was also picking up their filters and 5w30 synthetic for his Corvette and he is also quite satisfied with super-Tech.