i have a 2001 gmc yukon xl 8.1 and my manifold screw keep coming loose how

[cazh_it]

do i fix it its a star like screw? it makes a little whistling sound wen it comes loose i already had to replace all 4 cats and i don't want to do in again

 

[Mad Jack]

Add some Locktite red thread locker to the threads.