Oil Leak coming from oil valve? Options

[soltrain]

I just changed my oil for the first time this weekend - it was an interesting experience. The fools who changed the oil the last time musta used air tools to secure the oil filter because it took me about an hour and a half until I finally resorted to using a giant wrench to crush and turn the old filter off. I tried hammering a screwdriver in, but there's so little room to manuever, that it was impossible.

But anyways, after switching the oil and adding AutoRX, I also changed the oil valve. I purchased the fumoto valve, but wasn't sure how tight to install it, so I just hand-tightened it. The next day, I noticed small puddle beneath the oil valve, so I borrowed a friends cresent wrench and tightened it some more. Today, there is still a small leak, and I hope its from the valve - I'm not sure if I should tighten it some more or not. The instructions say 'don't over tighten.' How much is that? Using the wrench, I could still tighten it some more -- should I?