I was looking at my credit reports today and noticed that Equifax is showing an old car loan as still being open but paid. How is this effecting my credit score? Wouldn't leaving it this way help my credit since it gives me a longer credit history and the payment doesn't work against me in the debt to income ratio since it indicates paid off?

Every little detail factors into your credit score. I would call the creditor and make sure that you get that account closed so that it reflects on your report. Every little thing helps. I'm not sure how an open car loan would work towards your longer credit history. I know that with credit cards, they always say you should keep your oldest one open, but I'm not sure how that works with car loans.