Is that the cap (bolt) with a copper crush washer under it, and do you have an oil filter adapter with a vernatherm in it? If so, it is a cover over where there used to be a 'viscosity' bypass valve and spring, that is now not needed because of the vernatherm - unless you want to get rid of the vernatherm and replace the bypass valve. The crush washer should be replaced whenever you take this bolt off. I'm not sure it can be heat treated and re-used like spark plug gaskets can. If it's this crush washered plug you're talking about, the correct torque is to tighten until the shoulder of the bolt contacts the washer, and then you turn the bolt another 'X' number of degrees (crushing and sealing the washer). The number depends on the size of the bolt and the thread count - I think it's something like 230 degrees (about 2/3 turn), but not sure. I have a table with these different limits out at the hangar, but I got them from somebody on this website, so maybe someone can chime in and help out. If it is over torqued, it will eventually leak.... ask me how I know.... If this isn't the bolt you're talking about, then it's probably the one Mel is referring to. If it is, let me know and I'll see if I can get that torque table for you.
