It's recommended to use an IPA prior to application. I was fortunate enough to be training in Huntington Beach at Rich Evans shop when SF was first introduced. Rich Evans did an Avalanche with it and the results were more than satisfactory. It would have cost the customer $3000 to replace the...
I've used OPC 4:1 on jean stains and a brush on an Avalon leather seat. Like paint, just work your way up from 10:1. I would stop at 3:1 though. Test an area first. Good Luck.