That is incorrect...

If you get a loan for $8k and are FINANCING 8k, you will get a payment on that 8k that is not changed depending on how much you pay off.

So, for arguements sake,  lets say your payment would be $200/month initially on 8k.

1 month later, you pay off 5k of your loan, leaving 3k.

You will still pay the 200/month on the remaining balance, allowing you to pay it off early, but it will not  change monthly payment unless you refinance - but I find it hard to think that a financial institution would refinance for 2-3k..

Good Luck!