Amsoil Signature Series oils are $7.85 a quart as a preferred customer. Most synthetics at the Auto parts stores cost more than this and even if you throw in shipping cost for the Amsoil it is still cheaper in some instances. You are also getting a TRUE synthetic oil. Not something that is a highley refined group III base stock which is a conventional oil base stock. If you want to go for extended drain intervals I don't think you will find a better motor oil.
2012 GT Premium, Ingot Silver, Brembo package, 3.73's, Clear Bra, GT500 Axle Backs, tint.