I just changed my oil the other day, i dont know if that is relevent or not....but for the past few days maybe a week i noticed a knocking in the engine and i have been putting 91 octane in and just incase it was the gas i put 93 in this time to see what happens..

97 a4 1.8t
oil-valvoline SYNpower Full synthetic 10w 30 i think

 

You should be using 5w 30 or 0w40.

If you are not, that could be why its noisier now.

 

You're not sure what type of oil you put in your car? Eeek

I run M1 0w40 synthetic in mine. As Ace mentioned, 5w30, or 0w40 is best