One more thing to think about, the cover is aluminum, block cast iron. Electrolysis. Over time the cover corrodes, I've replaced a few because of this problem. What looks like a leak around a bolt turns out to be a tc cover. A bad sign? Moisture in the oil. Look at it good, water will travel far from where it actually leaks. Other than a messed up gasket, bad cover is the only time I had a leak.