Hi I was driving home when I noticed when I hit the gas that it would start ticking loud something in the motor. When you start off it ticks and then quiets down. Then as you keep going it is intermittent. The oil level was way low. It was three quarts low and I think it still needs 1 quart more. My dad seems to think it is the valve. What is the real name for it and how hard is it to replace. I want to try if it is too hard I will let a shop do it. How much do they usually charge. Thanks.