This may or may not help. I use the 3/8" pipe hole on my GMCs for the oil filters and also for external pumps when I use them. I drill the out to a size I feel comfortable with and use -10 lines and never have had an oil problem. I race these so I do not khow about street use and a -8.

Good Luck

216.158 MPH 12-Port 302 GMC on 70% 171.0 MPH 302 stock head on gasoline 7 years later