I would not switch oil. You still have no proof that the noise is lubrication-related. Get out the torque wrench and check those plugs!

 

It's been about 50k miles since they've been changed. Might as well just go ahead and change them while I'm in there. What's the correct torque spec?

 

28 lbs dry no anti seize. its equally important to make sure the coils are tight but not to tight in there mounting bolt. I believe loose coils are the root cause of many blow outs. The coil has a bushing and they are supposed to move in it but not loosely..