So many different answers and opinions on this, gonna do an oil change on the 2011 5.0 coupe I just bought.
Specs on both:
FL 500S:
By-Pass Valve Setting-PSI: 8
Anti-Drain Back Valve: Yes
Max Flow Rate: 10-12 GPM
FL 820S:
By-Pass Valve Setting-PSI: 16
Anti-Drain Back Valve: Yes
Max Flow Rate: 11-13 GPM
Specs on both:
FL 500S:
By-Pass Valve Setting-PSI: 8
Anti-Drain Back Valve: Yes
Max Flow Rate: 10-12 GPM
FL 820S:
By-Pass Valve Setting-PSI: 16
Anti-Drain Back Valve: Yes
Max Flow Rate: 11-13 GPM