The discussion about not using cheap bolts in the driveline should also be applied to brass fittings. Both Home Depot and Lowes carry the same line of JUNK brass fittings. I've bought several types of fittings while working on the copper air lines and they're all CR*P. The brass is too soft and the threads are very shallow. While trying to tighten a coupler on a 3/8" line they just kept stripping if you try to tighten them up to where the soapy liquid quites bubbling as you check for leaks. I ended up getting fittings at NAPA and also an old type plumping supply house. VERY noticeaible difference in the quality of fitting. All the better ones tightened up first time with no leaks. I wasted a bunch of time and $ working with and then replacing these JUNK fittings.