Been battling this issue to no avail, I am constantly getting oil on my spark plugs threads and on number 2 cylinder will foul out the plug to where it wont even fire. I am running a prc 260 ls3 head and I have rtv the rocker bolt holes. I have no idea where the oil is coming from. Didn't have this issue until these heads ? Any advise. The motor does use oil but does not leak, going to do a leak down test this weekend. After an hour driving all the plugs are burning good except one and all have oil on the threads.