Racor suggest you divide your engine hp by 20 to give the CFM of the filter. This gives 20 for the ISL 400 so the CV6001 would be the one to choose. This is around $300. You then need to add hose connectors which are Racor specific (the thread is no-standard), but I found these on EBay for $20. I decide to capture the oil in a container rather than try to return it to the sump so you may need to add that cost to.
John and Mary Knight
2015 Ventana 4311, 2015 Cadillac SRX