I just Bought my 06 mazda 6i about 5 months ago i started to hear some kocking coming from the engine compartment at 9k miles so i took the car in, they said that it was lower engine knocking and it was caused by my lack of chainging the oil, now i know it should have been done at 7500 but i figured it would be ok and i was very busy so i held off a little, anyways they say they wont fix it under my warranty and it will need a new engine. I was wondering if there was anything i could do and if it really was my fault or a faulty engine???