Oil Leak

Oil is leaking from the oil filter cover on my LTR. I recently replaced the stock oil filter cover bolts with stainless ones, but it was leaking before that. I tightened it down after every oil change but was careful not to tighten it to much due to the stock bolts being soft. Then, after I broke one by barely turning it, I got some stainless ones from Advance Auto Parts, and tightened them down, but not to much as to booger the threads on the inside of the motor, knowing that the stainless bolt is stronger than the threads in the motor. Im sure its tight enough, but why is oil still leaking? Has the o-ring went bad that quick?