... you could do that you would get the miles but lose the intrest YOUR money would make over the life of the loan. So you would give up earnings for miles and I think the earnings would be much greater compared to 0%. That's why I said if I get 0%, it's a no-brainer, finance everything!

I use my MasterCard for everything like you and rack up miles. I pay it off but still incur slight interst charges now and then, but they are very small compaired to the benefits of the Rewards. Since the rewards amount to about 1%, if you ever carry a balance it wipes out the benefits quickly. Before Exxon and Mobil merged I had a Corporate American Express and Mobil would allow us to keep the miles we racked up. It was nothing to put $10,000 in a month in (company expence) charges- MAN that was FREE money for me. I sure MISS that part- ExxonMobil was not so generous with their Corporate card. Half the time I was scared to use it with all the damn restrictions Exxon said what it could not be used for.