So...I had to replace my Y pipe the other day and before doing so, noticed the slightest sound of engine knock. So after replacing the Y pipe I changed the oil. I have always used synthetic 5w30 but figured I'll use 10w30 to see if that would make the slight engine knock go away. Bad choice (I think) Now, the engine knock is very constant while idling and even worse when revved up to 1100rpm after 1100 it seems to get quieter up until 2000rpm and then I can no longer hear it. Was this due to using 10w30 or something having to do with the Y pipe and the catalytic coverters? Also there is a faint burning smell. I'm going to drain the oil and put in 5w30 tomorrow to see if that helps any but in the meantime, any thoughts/suggestions on what it could be or what to do?

Thanks

 

Replace your gas. Maybe you had some bad gas.

 

It shouldn't be that. I've only used Shell 91 for over a year now and never heard this noise until replacing the Y pipe and changing to 10w30. Took the car over to a large parking lot tonight, and while in drive and giving it a little bit of gas I could hear the knocking as well and it matching the RPMs.

 

its not the oil - 10w-30 is good, thats what I use

if you actually have a knock consider other things...bad gas, spark plugs, etc

 

I'm pretty sure it's a rod bearing. I haven't changed the plugs yet, but I used some Lucas Oil Stabilizer and it seemed to quiet down the knock.