Is the unit leaking itself or is it leaking past the threads? If its leaking past the threads, remove it, apply a thin coat of white pipe sealing compound on the threads and reinstall. If the sender itself is leaking, its time for a new sender
Now Im confused, an oil sending unit has no bolts and no gasket. The oil sender is screwed into the block on the right side just behind the timing cover
That would be the oil pump. You will need to take it apart and examine the sealing surfaces. How did you set up the gears?
That is the oil filter housing adapter........and from what I see in that pi it looks like there is oil above where the parting line and gasket is. To me that looks like it's coming from the pan area. What I have done by on not just buicks........clean everything super good, brake clean, wiper with clean rags a few times, then go over it with alcohol, wat for it to dry, then get you some right stuff........I feel it's better than standard rtv..........and go around where the pan and cover mee. All the way, might have to get a little wooden tool or spreader, or screw driver even to help push it back into some of the tighter areas..........but on seeps like this you can actually seal them externally this way. Might take a few times.
There;s way more to it than that. Read Larry's thread, then read it again http://www.v8buick.com/index.php?threads/oil-pump-clearances-and-oil-pressure.326597/#post-2732527
X2 on what Ben said- spray it down with brake clean and hit it with compressed air. Get it clean and dry. Then start the car and pinpoint where exactly the leak is coming from. Its hard to tell when everything is soaked
