I would simply use a thinner nut, 12 point. You can grind down the stud and still keep the top of the stud flat by using the side of a grinding wheel on a bench grinder. Or grind down the oil pump body. I'm sure that this has happened before and apparently the company's don't want to take the time necessary to eliminate the problem. All they would have to do is use a shorter stud and nut.
