I am mounting a 2-axis rail system in the ceiling of my shop to hold a half ton hoist and want to properly size the mounting screws for maximum holding power. I will use 5/16" x 4" hex head lag screws into 2x8 rafters. I went on the internet to find the proper pilot hole size for soft wood and the first hit was 9/64", nearly 3/16" smaller than the screw size. It split the (test) wood. I went back to the internet and found pilot hole sizes for soft wood ranging from 9/64" to 15/64". Really? What do the sages recommend to optimize holding power without splitting in a 2x8?