I purchased a car around 12600 (with a 1000 down payment included 1000-13600) with a credit score around 550. Americredit gave me an interest rate of 18%. Five months later my credit score is 646 and Im expecting it to raise around 669 early September (raises 20 to 24 points monthly). My question is should I wait a year to refinance? The car sales man told me that I shouldn't refinance bad credit. Will applying to get my loan refinance lower my credit score? Will credit lenders prefer a year worth of on time payments on my credit history?. Will changing my creditor lower my credit score?